Distributed cable modem termination system with software reconfiguable mac and phy capability

ABSTRACT

Distributed and highly software reconfigurable CMTS (CMRTS) device, based on MAC and PHY units with FPGA and DSP components, for a HFC CATV network. The various CATV RF modulators, such as QAM modulators, may be divided between QAM modulators located at the cable plant, and remote QAM modulators ideally located at the fiber nodes. A basic set of CATV QAM data waveforms may optionally be transmitted to the nodes using a first fiber, and a second set of IP/on-demand data may be transmitted to the nodes using an alternate fiber or alternate fiber frequency, and optionally using other protocols such as Ethernet protocols. The nodes will extract the data specific to each neighborhood and inject this data into unused QAM channels, thus achieving improved data transmission rates through finer granularity. A computerized “virtual shelf” control system for managing and reconfiguring the FPGA and DSP based CMTRS units is also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/555,170 “DISTRIBUTED CABLE MODEM TERMINATION SYSTEM WITH SOFTWARERECONFIGUABLE MAC AND PHY CAPABILITY”, filed Jul. 22, 2012; applicationSer. No. 13/555,170 is a continuation in part of U.S. patent applicationSer. No. 12/907,970, “HFC CABLE SYSTEM WITH SHADOW FIBER AND COAX FIBERTERMINALS”, filed Oct. 19, 2010, and also a continuation in part of U.S.patent application Ser. No. 13/346,709, “HFC CABLE SYSTEM WITH WIDEBANDCOMMUNICATIONS PATHWAY AND COAX DOMAIN NODES”, filed Jan. 9, 2012; andalso a continuation in part of application Ser. No. 13/035,993, “METHODOF CATV CABLE SAME-FREQUENCY TIME DIVISION DUPLEX DATA TRANSMISSION”,filed Feb. 27, 2011, the latter two of which were also a continuation inpart of application Ser. No. 12/907,970; these applications in turn inturn claimed the priority benefit of U.S. provisional application61/385,125 “IMPROVED HYBRID FIBER CABLE SYSTEM AND METHOD”, filed Sep.21, 2010; and U.S. patent application Ser. No. 12/692,582, “DISTRIBUTEDCABLE MODEM TERMINATION SYSTEM” filed Jan. 22, 2010; application Ser.No. 13/555,170 is also a continuation in part of U.S. patent applicationSer. No. 12/692,582, “DISTRIBUTED CABLE MODEM TERMINATION SYSTEM” filedJan. 22, 2010; application Ser. No. 13/555,170 also claims the prioritybenefit of U.S. patent application Ser. No. 13/478,461, “EFFICIENTBANDWIDTH UTILIZATION METHODS FOR CATV DOCSIS CHANNELS AND OTHERAPPLICATIONS”, filed May 23, 2012; 13/478,461 in turn claimed thepriority benefit of U.S. provisional application 61/622,132, entitled“EFFICIENT BANDWIDTH UTILIZATION METHODS FOR CATV DOCSIS CHANNELS ANDOTHER APPLICATIONS”, filed Apr. 10, 2012; application Ser. No.13/555,170 also claims the priority benefit of U.S. patent applicationSer. No. 13/400,415, “METHODS OF ADAPTIVE CANCELLING AND SECONDARYCOMMUNICATIONS CHANNELS FOR EXTENDED CAPABILITY HFC CABLE SYSTEMS”,filed Feb. 20, 2012; application Ser. No. 13/555,170 also claims thepriority benefit of U.S. provisional application 61/511,395, “IMPROVEDHYBRID FIBER CABLE SYSTEM AND METHOD”, filed Jul. 25, 2001; all have theinventor Shlomo Selim Rakib; the contents of all of these applicationsare incorporated herein by reference.

BACKGROUND OF THE INVENTION

Cable television (CATV), originally introduced in the late 1940's as away to transmit television signals by coaxial cables to houses in areasof poor reception, has over the years been modified and extended toenable the cable medium to transport a growing number of different typesof digital data, including both digital television and broadbandInternet data.

One of the most significant improvements occurred in the 1990's, when anumber of major electronics and cable operator companies, workingthrough CableLabs, a non-profit R&D consortium, introduced the Data OverCable Service Interface Specification (DOCSIS). First introduced in thelate 1990's as DOCSIS version 1.0, and upgraded many times since(currently at DOCSIS version 3.0), the DOCSIS standard defines thePhysical Layers (PHY) and Media Access Control (MAC) layers needed tosend relatively large amounts of digital data through coaxial cablesthat were originally designed to handle analog standard definitiontelevision channels.

Originally, analog television (in the US) transmitted televisionchannels as a series of roughly 6 MHz bandwidth radiofrequency waveformsat frequencies ranging from about 54 MHz (originally used for VHFChannel 2) up to about 885 MHz for now no-longer used UHF channel 83.This television signal was transmitted as a combination amplitudemodulated signal (for the black and white portion), quadrature-amplitudemodulated signal (for the color portion), and frequency modulated signal(for the audio portion), and this combined signal will be designated asa Frequency Division Multiplexed (FDM) signal.

With the advent of digital television and high definition televisionstandardization in the late 1980's and early 1990's, the basic 6 MHzbandwidth spectrum of analog television was retained, but the modulationscheme was changed to a more sophisticated and higher data rateQuadrature Amplitude Modulation (QAM) scheme, which can encode digitalinformation onto a very complex QAM analog signal (waveform).

The DOCSIS standard built upon this analog and digital TV foundation,and specified additional standards to provide broadband Internetservices (Internet protocols, or IP), voice over IP, custom video ondemand, and other modern services based upon the QAM data transmissionwaveforms (generally also 6 MHz wide) previously established for digitaland high definition television.

As a result, by a series of steps, simple coaxial cables, originally runat great expense to millions of households starting from the 1950's and1960's, has been gradually upgraded to accommodate ever increasingdemands for digital data. At each house (or apartment, office, store,restaurant or other location), the household connects to the CATV cableby a cable modem, uses the cable modem to extract downstream DOCSISdigital data (frequently used for high-speed Internet), and injectupstream DOCSIS digital data (again frequently used for high-speedInternet applications).

Unfortunately, even in a coax cable, there is a finite amount ofbandwidth available to transmit data. Coax cables and their associatedradiofrequency interface equipment have typically only used thefrequency range under about 1000 MHz, and so there are limits to howmuch data the 1950's era coaxial cable can ultimately transmit.

By contrast, optical fiber (fiber optics, fiber) technology, which usesmuch higher optical frequencies (with wavelengths typically in the800-2000 nanometer range), can transmit a much higher amount of data.Optical fiber data rates typically are in the tens or even hundreds ofgigabits per second. Indeed, the entire RF CATV cable spectrum from 0 to1000 MHz can be converted to optical wavelengths (such as 1310 nm or1550 nm), be carried over an optical fiber, and then be converted backto the full RF CATV cable spectrum at the other end of the fiber,without coming close to exhausting the ability of the optical fiber tocarry additional data.

This conversion process can be achieved by relatively simple optical todigital or digital to optical converters, in which the CATV RF waveformsare simply converted back and forth to a light signal by simple (“dumb”)E/O or 0/E converters, located in nodes that connect optical fibers toCATV cable (fiber nodes).

The higher data carrying capacity of optical fibers allows additionaldata to be carried as well, and in some schemes, the essentially analog(digital encoded in analog) spectrum of CATV waveforms is carried at oneoptical wavelength (such as 1310 nm), and digital data encoded byentirely different protocols may be carried at an alternate opticalwavelength (such as 1550 nm). This dual scheme is often referred to aswavelength-division multiplexing.

Optical fiber technology has been widely used for high capacity computernetworks, and these networks often do not use the DOCSIS protocols orQAM protocols to transmit data. Rather, these high capacity computernetworks often use entirely different types of data transmissionprotocols, such as the Ethernet protocols IEEE 802.3ah, 1000BASE-LX10,1000Base-BX10, and others. These networks and protocols are oftenreferred to as GigE networks, which is an abbreviation of the Gigabytespeeds and Ethernet protocols used for fiber based computer network.

Thus if a user desires to transfer computer data from RF QAM waveformstransported over a CATV cable to a high speed GigE fiber network, thedata must be transformed back and forth between the DOCSIS cable QAMwaveforms and the alternate protocols (often Ethernet protocols) used infiber GigE networks.

Although ideally, the best way to satisfy the ever increasing householddemand for digital data (e.g. video—on demand, high speed Internet,voice over IP, etc.) would be by extending optical fiber to eachhousehold, this would be an incredibly expensive solution. By contrast,cable based CATV solutions have already been implemented for tens ofmillions of households, and this expense has already been borne andamortized over decades of use, starting from the 1950s. As a result, itis far more economically attractive to find schemes enable the existing,if bandwidth limited, CATV cable system, to be further extended to meetthe ever growing demands for additional data.

Cable System Components:

At the plant or “head” end of a typical CATV cable network (cable), thechallenging task of combining the many different types of data (analogtelevision channels, digital television channels, on-demand channels,voice over IP, DOCSIS channels, etc.) and sending this data to users(households) scattered through many different neighborhoods in variousregions of towns, cities, counties and even states is handled, in part,by Cable Modem Termination Systems (CMTS) devices. These CMTS devicesconnect to the various data sources (television stations, video servers,the Internet, etc.) at one end, and to many different CATV cables at theother end.

Typically the CMTS device will have a connection to the various datasources and appropriate data switches (such as a Level 2/3 switch) atone end, and often a plurality of different line cards (often physicallypackaged to look like blade servers, and put into a main CTMS box thatholds multiple line cards) at the other end. Each line card willtypically be connected to either cables or optical fibers that travelaway from the cable head towards various groups of multipleneighborhoods, where typically each group of multiple neighborhoods willbe in a roughly contiguous geographic region. The line card cables oroptical fibers are then typically subdivided further by varioussplitters and nodes, and eventually the signals flow to the individualneighborhoods, each served by its own CATV cable.

At the neighborhood level, an individual CATV cable will serve betweenabout 25 and a few hundred households (houses, apartments). Theseconnect to the individual cable by cable modems. Here each cable modemwill be considered to be a household or “house”, regardless of if thecable modem serves a house, apartment, office, workplace, or otherapplication.

The CMTS line cards will typically contain at least the MAC and PHYdevices needed to transmit and receive the appropriate CATV signals.Typically the line card PHY devices will contain a plurality of QAMmodulators that can modulate the digital signals that a Level 2/3 switchhas sent to that particular line card, and send the signals out overcable or fiber as a plurality of QAM channels. The line cards will alsotypically contain MAC and PHY devices to receive upstream data sent backto the cable head from the various cables and cable modems in the field.

It is impractical to directly connect each individual neighborhood CATVcable directly to the cable plant. Rather cable networks are arranged inmore complex schemes, where the signals to and from many differentindividual neighborhoods are combined by the network prior to reachingthe cable plant or cable head. Thus each CMTS line card will typicallysend and receive signals to and from multiple neighborhoods.

Instead of sending and receiving data by cable, the various CMTS linecards can instead communicate to their various groups of neighborhoodsby optical fiber. However it is also impractical to run individualfibers directly from individual neighborhoods to the cable plant orcable head as well. Thus fiber networks are also usually arranged inmore complex schemes, where the signals to and from different individualneighborhoods are also combined by the optical fiber network before thesignals reach the cable plant or cable head.

At a minimum, the optical fiber network will at least typically split(or combine) the fiber signals, often by “dumb” optical fibersplitters/combiners (here called splitters) that do not alter the fibersignal, and the split signal then will be sent by sub-fibers to thevarious neighborhoods. There, the optical fiber signal can be convertedto and from a RF signal (suitable for the individual cable) by a “dumb”fiber node that itself simply converts the optical to RF and RF tooptical signals without otherwise altering their content. These hybridoptical fiber to cable networks are called Hybrid Fiber Cable (HFC)networks.

Prior art work with various types of CMTS systems and fiber nodesincludes Liva et. al., U.S. Pat. No. 7,149,223; Sucharczuk et. al. USpatent application 2007/0189770; and Amit, U.S. Pat. No. 7,197,045.

Typically, nearly all CATV users want immediate access to at least astandard set of cable television channels, and thus to satisfy thisbasic expectation, usually all CATV cables will receive a basic set oftelevision channels that correspond to this “basic” or “standard”package (which may include various commonly used premium channels aswell). Additionally, most users will wish access to a wide range ofindividualized data, and here the limited bandwidth of the CATV cablestarts to become more of a nuisance.

As a first step towards more efficient cable utilization, analogtelevision is being phased out, freeing much FDM bandwidth (analogstandard definition TV channels) that can be replaced by more efficientQAM channels carrying both digital TV and DOCSIS data. However phasingout old-fashioned FDM TV signals, although freeing up additional cablebandwidth, will at most satisfy the ever increasing household demand fordigital TV and DOCSIS services (data) for only a few years. Thusadditional methods to supply a greater amount of data, in particularon-demand video data, voice over IP data, broadband Internet (IP) data,and other data, are desirable.

DOCSIS standards:

Unless otherwise specified references herein to “DOCSIS” will refer tothe Cablelabs DOCSIS® 3.0 specifications. These are more specificallydefined in the following publications: Data-Over-Cable Service InterfaceSpecifications DOCSIS 3.0 Security SpecificationCM-SP-SECv3.0-113-100611; Cable Modem to Customer Premise EquipmentInterface Specification CM-SP-CMCIv3.0-101-080320; Physical LayerSpecification CM-SP-PHYv3.0-110-111117; MAC and Upper Layer ProtocolsInterface Specification CM-SP-MULPIv3.0418-120329; Operations SupportSystem Interface Specification CM-SP-OSSIv3.0418-120329. Additionaldocumentation can be found in the DOCSIS 3.0 Technical ReportsCM-TR-MGMTv3.0-DIFF-V01-071228; and CM-TR-OSSIv3.0-CM-V01-080926. Forpurposes of this specification, features that implement an otherwisecompatible subset of the DOCSIS 3.0 specification are termed a DOCSISsubset, and features that implement either additional functions notspecified in DOCSIS 3.0, or incompatible with DOCSIS 3.0, are termed“non-DOCSIS functionality”.

Remotely situated QAM modulators:

Liva et. al., in U.S. Pat. No. 6,933,016 taught a method of transmittingan information channel by a unique method of processing the informationchannel, transmitting the information channel to a destination by packettechniques, and then reconstructing the channel. Additionally Sawyer, inUS Publication 2003/0066087, taught a hybrid distributed cable modemtermination system having mini fiber nodes containing CMTS modulatorsremotely located from the head end.

Field-Programmable Gate Array (FPGA) Technology:

Field-programmable gate arrays (FPGA), a type of programmable logicdevice (PLD), are integrated circuit devices and “chips” designed toallow the configuration of the chip's various internal electricalcircuits to be reconfigured after the chip has been manufactured. FPGAscontain programmable logic blocks with reconfigurable connections thatallow the wiring between the various logic gates in the blocks to berewired, even after the chip has been incorporated into other devices.In addition to digital functions, FPGA can handle analog functions.Various mixed signal FPGA, with integrated analog to digital converters(ADC) and digital to analog converters (DAC) are also available.Examples of FPGA include the popular Artix, Kintex, Virtex, and Spartanseries of chips produced by Xilinx Inc., San Jose, Calif., the popularCyclone, Arria, Stratix series of chips produced by Altera Corporation,San Jose Calif., and others.

Digital Signal Processor (DSP) Technology:

Digital signal processor (DSP) devices and “chips” are microprocessorswith an architecture that is specialized for high speed digital signalprocessing. Although standard processors can perform complex signalprocessing as well, due to the nature of the standard instruction sethardware, complex signal processing often requires a large (hundreds,thousands, or more) number of instructions to perform complex functions.By contrast, DSP chips often contain at least some specialized hardwarefor digital signal processing, including circular buffers, separateprogram and data memories (e.g. Harvard architecture), very longinstruction words (VLIW), various types of single instruction multipledata (SIMD) instructions, fast multiply-accumulate (MAC) hardware, bitreversed addressing, special loop controls, and the like. Thisspecialized hardware allow complex signal processing to be done in arelatively few number of operations, thus often speeding up complexcomputations by many orders of magnitude in time. To further reduceprocessing time DSP are often constructed without memory managementunits, thus avoiding time delays due to memory management unit inducedcontext switching.

Examples of DSP include the popular C6000 series of DSP produced byTexas Instruments, Inc, Dallas Tex., the StarCore DSP produced byFreescale Semiconductor Holdings, Ltd., Austin Tex., and others.

Examples of the use of FPGA and DSP to produce dynamicallyreconfigurable communications devices include Dick, U.S. Pat. No.7,583,725, and Raha et. al., U.S. Pat. No. 7,724,815, both assigned toXilinx, the contents of both of which are incorporated herein byreference.

BRIEF SUMMARY OF THE INVENTION

Here, a new type of highly flexible and reconfigurable distributedfunctionality CMTS system and method for HFC networks is disclosed. Thissystem and method divides the various CMTS functions between cable plantCMTS devices, and remote fiber node CMTS (here called Cable Modem RemoteTermination Systems, or CMRTS) devices, under an overallcomputer-controlled, device and network configuration and datadistribution scheme.

In some embodiments, this computer controlled signal and datadistribution scheme may be configured to maximize the granularity(neighborhood specificity) of customized data delivered to individualCATV cables serving individual neighborhoods. In this type ofconfiguration, often the system and method can be further configured topreserve backward compatibility with legacy HFC networks and devices, aswell as to gracefully degrade from a higher level of standard andcustomized data delivery service, to the prior art level of standard andcustomized data delivery service, under many different CMRTS devicefailure scenarios. This type of configuration allows existing HFCnetworks to be gradually upgraded to provide improved custom (IP-ondemand) service to selected neighborhoods on a cost effective basis, andcan eventually allow all neighborhoods to be upgraded as demand andfinancing allows.

The disclosure relies, in part, upon a distributed CMTS design in whichRF transmitters (here usually exemplified by QAM modulators, but othertypes of RF modulation/transmission schemes may also be used) in theCMTS PHY section (used to ultimately provide the waveforms used to senddata signals to a given individual cable) are constructed from softwarereconfigurable FPGA and DSP devices, and then divided and distributedthroughout the HFC network. Here, in certain legacy embodiments, onoccasion some legacy QAM modulators may remain located in the PHY unitsof main (centralized, e.g.—cable head or cable plant) CMTS line cards onthe central CMTS units. However other software reconfigurable FPGA andDSP based RF modulators, such as QAM modulators are located in the FPGAand DSP based PHY sections of remote or distributed CMTS. These remoteCMTS units are here referred to as Cable Modem Remote Termination System(CMRTS) units.

Occasionally, to emphasize the fact that when constructed with FPGA andDSP MAC and PHY units, these CMRTS units can also be configured to givethem entirely new types of functionality, these CMRTS units will bereferred to in the alternative as FPGA-DSP CMRTS units. For brevity,however, the CMRTS nomenclature will prevail, and in general unlessotherwise specified otherwise, all CMRTS units discussed in thisspecification should be considered to be constructed with FPGA and DSPbased MAC and PHY units. Also for brevity, although this specificationwill often refer to a QAM transmitters and receivers, which produce andreceive a specific form of RF modulation popular in prior art DOCSISCATV cable implementations, unless otherwise specified, the inventionwill also contemplate other forms of RF modulation as well such as CDMAand OFDM modulation. Thus QAM should be understood as being but oneexample (albeit a very popular example) of the various RF modulationschemes contemplated by the present disclosure.

According to the invention, these CMRTS units will often be located atthe final network fiber nodes (FN) between the fiber portions of the HFCsystem, and the cable portions of the HFC system.

In one embodiment, the QAM modulators located in the centralized CMTSPHY sections may primarily focus on sending data, such as a standardizedpackage of cable TV channels and perhaps a basic level of DOCSISservice, which is generally requested by many neighborhoods in general.Thus, in a simplified example, the central QAM units in a central CMTSline card driving three cables in three neighborhoods would send thesame QAM signals to all three neighborhoods. At the same time, thiscentral CMTS unit and CMTS line card may optionally coordinate its work(i.e. divide the responsibility for generating QAM channels) with remoteor distributed QAM modulators located in up to three remote CMTS (CMRTS)units located in the in the final optical fiber nodes (FN) that connectthe fiber portion of the HFC network with the three cables that supplythe three neighborhoods.

The invention's CMRTS units will typically be designed to be both highlysoftware configurable to allow high operational flexibility withoutaltering the basic characteristics of the units MAC and PHY units.However according to the invention, there is an additional advantage inthat in addition to this operational flexibility, the basic hardwarecharacteristics of the CMRTS units MAC and PHY units can also be changedas needed. This is because the CMRTS units are designed with softwarereconfigurable FPGA and DSP based MAC and PHY units. This enables theCMRTS units to have an almost infinite number of different ways in whichthey can operate their remote or distributed QAM modulators (or other RFmodulators/transmitters) to send downstream data.

Additionally, due to the use of software reconfigurable FPGA and DSPbased MAC and PHY units, the ability of the CMRTS units to operatevarious types of RF packet processors that receive multiple RF bursts ofmodulated upstream data from various cable modems, demodulate thebursts, digitizes and reassemble this upstream data into packets, andretransmit this data back upstream, can be both hardware (e.g. changedto entirely different type of RF receiver and processor) and alsooperationally reconfigured by remote software as well. Theseimprovements over the prior art can not only can act simplify themanagement and configuration of the distributed CMRTS network, but canalso greatly expand its standard functionality as well.

In some configurations, in order to supply a standardized set of TVchannels and other services to the three cables in three neighborhoods,the central CMTS unit and central CMTS line card may have the QAMmodulators in the CMTS line card set to drive an optical fiber withmultiple QAM signals at optical wavelengths, with the QAM waveformsbeing such that these optical QAM waveforms can be directly converted toradiofrequency QAM waveforms with inexpensive “dumb” converters, anddirectly injected into the three cables to provide the basic level ofservice.

In order to supply data to drive the remote CMRTS QAM modulators, toprovide a higher level of service, various options are possible.

In a first option that is more backwards compatible with existing CTMSdesigns, the data to drive the remote CMRTS QAM modulators may be sentusing a separate Level 2 switch and separate optical fiber system,typically using digital Ethernet protocols. This Level 2 switch andsecond optical fiber system will operate largely independently of thecable plant CTMS unit. Here the operator of the cable plant CTMS unitmay simply configure the CTMS to have some empty QAM channels availablefor subsequent use by FPGA and DSP based MAC and PHY units in the remoteCMRTS units that are configured to act as QAM modulators, but otherwiseoperate the standard (prior art) CTMS according to normal methods.

In a second option that represents a more radical departure from priorCMTS designs, in addition to sending the standard set of CATV RF data,the centralized CMTS unit and CMTS line card also send additional datato the CMRTS units on a second communications media, and intelligentlycoordinate which information gets sent on the first communicationsmedia, and which information gets sent on the second communicationsmedia, in order to maximize overall system functionality.

One advantage of the invention's CMRTS units is that because they can bedesigned to be highly software configurable, and additionally to havesoftware configurable hardware as well due to FPGA and DSP based MAC andPHY components, the same CMRTS units can be reconfigured to work withthe first backwards compatible CMRT option, the second more radical CMTSoption (design), or a wide variety of other options as well. Because theCMRTS design is both software configurable and in some configurationscan allow for the pass through of prior art CATV RF to optical signals,the CMRTS can be configured to be also highly backward compatible asneeded, and can be implemented in a way that can be largely transparentto the cable operator until the higher functionality of the CMRTS isrequired.

For either the first or second option, the second communications mediaused to transmit data to the CMRTS may use a second optical fiber and analternative data transmission protocol, such as various Ethernetprotocols previously discussed. If this scheme was used, the data wouldrequire conversion, reformatting, and QAM modulation by the remote CMRTSunits. Here, for example, the FPGA and DSP units in the CMRTS unitscould be configured as QAM modulators that would then provide aradiofrequency (RF) QAM signal that can be injected into the cable, andrecognized by cable modems attached to the various cables. In thisconfiguration, to avoid conflicts, the frequency (or at least timeslice) of the QAM waveforms provided by the CMRTS units should differfrom the frequency (or at least time slice) of the QAM waveformsprovided by the central CMTS QAM modulators.

Alternatively, this second communications media may carry data to theCMRTS units using the same (first or main) optical fiber that is alsoused to carry QAM signals from the CMTS. In this alternativeconfiguration, the CMRTS data can be carried at an alternate wavelength.For example, the CMTS data, which may carry the main package of CATV TVstations and perhaps some DOCSIS services, may communicate using a 1310nm optical wavelength, while the CMRTS data, which may carry thesupplemental IP/On-demand data, may communicate using a 1550 nm opticalwavelength. This type of scheme is often called wavelength-divisionmultiplexing. As previously discussed, this supplemental CMRTS data neednot be encoded using CATV compliant QAM modulation (although it couldbe), but rather may be carried using different protocols and modulationschemes, such as the previously discussed GigE Ethernet protocols. Hereagain, because of the fact that the CMRTS units have highlyreconfigurable FPGA and DSP based MAC and PHY units, almost any protocoland modulation scheme, including protocols and modulation schemes thatwere not even invented at the time that the various CMRTS units werefirst placed in the field, may be used.

This second communications media, being an optical fiber media itself,will generally be capable of transmitting far more IP/on-demand datathan could be possibly be transmitted over a standard CATV cable.Unfortunately, at the end of the fiber network, we again reach the CATVcable bandwidth bottleneck, which again limits the amount of data thatcan be transmitted to any given individual neighborhood.

The invention relies, in part, upon the observation that at the presentlevel of rather coarse granularity (where multiple neighborhoods areserved by the same CATV QAM signals) the aggregate demands for IP-ondemand data from multiple cables serving multiple neighborhoods mayeasily saturate the limited CATV bandwidth. However at a finer level ofgranularity (where each neighborhood might get its own customized CATVsignal), the IP-on demand data for an individual neighborhood is morelikely to fit within the limited bandwidth of each neighborhood's CATVcable. The trick is thus to avoid overloading each neighborhood'sparticular CATV cable bandwidth by picking and choosing the mix ofstandard QAM and QAM IP/on-demand signals are delivered to eachneighborhood. This scheme of delivering a potentially ever changing mixof neighborhood specific CATV channels, as well as providing acapability to provide services different from the current DOCSISstandard (presently DOCSIS 3.0) creates some rather complex networkmanagement issues, however.

As previously discussed, to cope with these complex network managementissues, this disclosure also relies, in part, upon a sophisticatedcomputer control system to frequently (or even continually) adjust theoperation of both the central CMTS and the remote CMRTS units tocarefully balance user demands for standard data (e.g. standard QAM TVchannels and perhaps a limited standard level of DOCSIS service) andcustomized data (e.g. IP/on-demand data). This computer control systemcan additionally be assigned the responsibility for configuring theCMRTS hardware via programming/configuring the various FPGA and DSPcomponents that comprise the MAC and PHY CMRTS units.

The computer control system may, for example in addition to configuringthe various CMRTS MAC and PHY units via configuring their respectiveFPGA and DSP components, manage the available bandwidth on the variouscables that serve the various neighborhoods. When used in the backwardcompatible first option mode, the “standard” QAM channels that aretransmitted are fixed by the cable operator in advance, and these remainrelatively constant. When used in the higher throughput and more radicalsecond option mode, the computerized system may vary both the “standard”QAM channels being transmitted by any given central CMRT line card, andthe user-customized or “premium” IP/on-demand QAM channels beingtransmitted by the remote CMRTS units.

In CATV jargon, the various CMTS systems at the cable head are oftenreferred to as a “shelf” or “CMTS shelf”. Although the inventiondistributes the functionality of the CMTS unit from the cable head tothroughout the entire network, from a network management perspective, insome embodiments, it may be simpler for the other network equipment andsoftware to continue to communicate with this network distributed CMTSas if it was still a single cable plant or cable head CMTS. Thus, in oneembodiment, this CMTS and CMRTS computer control system and softwarethat manages the network distributed CMTS will also be called “virtualshelf” hardware and software, because the computer control system mayboth manage the complex configuration issues involved in running adistributed CMTS system, and then shield this complexity from the restof the system when needed. Thus the remainder of the cable plant systemneed not be redesigned to handle the distributed CMTS functionality, butmay continue to address the invention's distributed CMTS as if it was aprior art non-distributed CMTS.

Thus the virtual shelf hardware/software system may, for example, takeas inputs, user demand over multiple neighborhoods for basic TV channelsand basic DOCSIS services, user demand in individual neighborhoods foradvanced or premium on-demand TV or premium DOCSIS IP service (IP-ondemand), and the limited number of total QAM channels that can becarried over cable.

In the first option, the virtual shelf system will simply work usingwhatever empty QAM channels are made available by the cable operator,and will work to optimize data to users within this overall constraint.

In the second option, in order to send still more data, the virtualshelf system may be much more active. It may, for example, elect todirect the QAM modulators in the PHY unit of a central CMTS line card tostop sending signals on one QAM channel (frequency), in order to free upthis QAM channel (frequency) for a neighborhood specific QAM channel(frequency).

In a third option, in order to send and receive even more data, thevirtual shelf system may even send data to the FPGA and DSP based MACand PHY units of the various CMRTS units in the field and instruct theMAC and PHY units to reconfigure themselves to handle additionalfunctionality beyond the present DOCSIS 3.0 standard (i.e. non-DOCSISfunctionality). This additional functionality can, as needed, beproprietary to that particular CATV cable operator and may not otherwiseneed to be a recognized standard. This feature enables different cableoperators to further differentiate their services from each other.

In general reconfiguring the basic functionality of the MAC and PHYunits in the various CMRTS units may be a comparatively rareevent—perhaps more often than a field hardware upgrade, but notnecessarily a daily activity either. By contrast, often on a morefrequent basis (e.g. perhaps even many times a day), the virtual shelfsystem then instruct previously FPGA and DSP configured GigE PHY unitson the same central CMTS line card to send neighborhood specific(IP/on-demand data) to those neighborhoods using the secondcommunications media and by an Ethernet modulated transmission protocol.The virtual shelf system may then instruct previously FPGA and DSPconfigured MAC and PHY units on the remote CMRTS unit on the fiber nodeserving the target neighborhood to take this IP/on-demand data from thesecond communications media, decode and QAM modulate the data, andinject this now RF modulated QAM data on the cable for that particularneighborhood using the now empty QAM channel (frequency).

The virtual shelf system can also instruct another remote CMRTS unit ona different fiber node serving a different neighborhood to take theIP/on-demand data for this neighborhood from the second communicationsmedia, decode and QAM modulate this data and inject this now RFmodulated QAM data on the cable for this neighborhood as well.

Note that by this method, even though both neighborhoods may receivesome common QAM channels and data from the same centralized CMTS linecard, the overall CATV QAM channels are not the same. Rather, at leastfor the IP/On-demand data, the same QAM channel (frequency) now carriesdifferent data for the two different neighborhoods.

Using these systems and methods, the effective data carrying capacity ofthe various cables and QAM channels has been increased. Yet, at the sametime, if the centralized computer system (virtual shelf) is properlyconfigured, most of the complexity of the switching arrangement can beselectively hidden from both the upstream (cable plant) and downstream(cable modem) systems, thus enabling good backward compatibility withexisting HFC equipment.

The use of FPGA and DSP based MAC and PHY units on the CMRTS units,particularly remotely configurable FPGA and DSP based MAC and PHY units,allows additional functionality to be easily implemented as well. Thisadditional functionality can include an ability to handle non-DOCSIS RFwaveforms such as QAM, CDMA, or OFDM waveforms. It can also include anability to configure the a particular CMRTS RF modulators (e.g. QAMmodulators) to pre-distort or customize the RF waveforms emitted by thatCMRTS unit in order to, for example, correct for RF signal impairmentson that stretch of CATV cable. Alternatively, the MAC and PHY units maybe configured to allow the RF receivers on board the CMRTS units tobetter equalize or adjust of for distorted upstream RF signals (oftenoriginating from household cable modems).

Additionally, the reconfigurable FPGA and DSP based MAC and PHY unitscan be reconfigured to allow for narrower spacing between regularlyspaced communications channels, thus increasing throughput.

CMRTS units employing software reconfigurable FPGA and DSP based MAC andPHY units can be used for other CATV applications and functionality aswell. Examples of such other applications include the applicationsdescribed in parent U.S. patent application Ser. Nos. 12/907,970;13/346,709; U.S. provisional applications 61/385,125 and 61/622,132; andU.S. patent application Ser. Nos. 12/692,582 and 13/478,462. Thecontents of all of these applications are incorporated herein byreference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an overall view of the various frequencies and datachannels allocated for a typical CATV cable carrying legacy analogtelevision FDM channels, QAM digital television channels, and varioustypes of DOCSIS data.

FIG. 2 shows an example of a prior art HFC cable system transmittingdata from the cable head to various individual cables using opticalfibers and optical fiber nodes.

FIG. 3 contrasts the difference between a prior art optical fiber tocable (fiber) node and the invention's improved cable modem remotetermination system (CMRTS) fiber node.

FIG. 4 shows how the invention's improved CMRTS fiber node can alsotransmit a greater amount of upstream data.

FIG. 5 shows how one embodiment (here the second option is shown) of theinvention's distributed cable modem termination system, working with anadvanced CMTS at the cable plant, can distribute a greater effectiveamount of downstream data to various CATV cables serving multiple usersin different neighborhoods.

FIG. 6 shows additional details of how some embodiments of the CMRTSfiber nodes may be constructed and operate in the second option.

FIG. 7A shows additional details of the CMRTS fiber nodes.

FIG. 7B shows additional details of CMRTS fiber nodes employing FPGA andDSP based MAC and PHY units, here configured to reproduce the samefunctionality as previously shown in FIG. 7A.

FIG. 8 shows an overview of how the distributed cable modem system maybe configured by way of “virtual shelf” software that controls theoperation and data flow of the system's CMTS and CMRTS devices.

FIG. 9 shows how an alternative embodiment (here the first option isshown) of the invention's distributed cable modem termination system,working with a prior art CMTS, can distribute a greater effective amountof downstream data to various CATV cables serving multiple users indifferent neighborhoods.

FIG. 10 shows additional details of how an alternative embodiment of theCMRTS fiber nodes may be constructed and operate in the first option.

FIG. 11 shows how the FPGA and DSP components of the MAC and PHY unitsof a CMRTS fiber node can be reconfigured to implement a filter banktransmitter, which may be a QAM transmitter.

FIG. 12 shows an example of the division of labor between the singlehandling steps handled by the FPGA portion and the DSP portion of theMAC and PHY units of a FPGA and DSP based CMRTS unit. Here a TDMA burstreceiver implementation is shown. The lower portion of FIG. 12 shows anexample of a superhetrodyne receiver implementation, most useful whenthe various upstream CATV channels are not regularly frequency spaced.

FIG. 13 shows how the FPGA and DSP components of the MAC and PHY unitsof a CMRTS fiber node can also be reconfigured to implement a filterbank receiver, which may be a QAM receiver. This configuration is mostuseful when the various upstream CATV channels are regularly frequencyspaced.

FIG. 14 shows a simplified flow diagram of some of the signal flowprocessing steps, often handled by the DSP portion of the FPGA and DSPbased CMRTS MAC and PHY units.

FIG. 15 shows an alternative view of the CMRTS based CATV network from asoftware management perspective.

FIG. 16 shows an alternative embodiment in which the CMRTS unit isconfigured to feed multiple electrical RF or data outputs, such as fourCATV cable outlets, or alternatively a mix of CATV cable outlets andother electrical outputs, such as data ports (e.g. GigE ports) and/ortelephony ports.

FIG. 17 shows an alternative embodiment in which the CMRTS unit isconfigured to feed multiple electrical RF or data outputs, and isfurther configured to connect directly to a single household, which maybe a single house or a multiple unit facility such as an office buildingor apartment house.

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment, the invention may be a distributed Cable ModemTermination System (CMTS) for a Hybrid Fiber Cable (HFC) network. Thissystem will typically consist of multiple parts.

In some embodiments, the system will work essentially independently ofthe CMTS at the cable plant, and will essentially act to supplement thefunctionality of prior art CMTS by adding a minimal amount of newequipment at the cable plant. Here, this new equipment at the cableplant cable will mainly consist of a Level 2/3 switch, a virtual shelfmanagement system (to be described), and appropriate MAC and PHY devicesto send and receive data along optical fibers. The prior art cable plantCMTS continues to operate as before, with the one exception that thecable operator should provide for some empty channels in order toprovide space for the new channels provided by the invention.

In other embodiments, parts of the system will be embedded into anadvanced CMTS head with at least a first packet switch, a first MAC(Media Access Control), and a first PHY (Physical Layer) capable ofsending and receiving data from a layer 2-3 switch to a first end of afirst optical fiber as at least a plurality of first digitally encodedanalog QAM waveforms (first optical signals).

In some embodiments, The CMTS head may also have a second MAC and asecond PHY capable of sending and receiving data from the layer 2-3switch to either the first end of the first optical fiber, or the firstend of a second optical fiber. If the first end of the first opticalfiber is used, typically the second PHY will send and receive data usingan alternate wavelength and often an alternative data transmissionprotocol such as an Ethernet protocol, although QAM waveforms may alsobe used). For example, the first wavelength may be 1310 nm, and thesecond wavelength may be 1550 nm. In general, the two differentwavelengths will be spaced apart enough to avoid crosstalk, often withspacing of 20 nm, 50 nm, 100 nm, or more depending upon the bandwidth ofthe optical signals.

Alternatively the second MAC and second PHY can send this data out usingthe first end of a second optical fiber. In both cases, these aredesignated as the second optical signals. For simplicity and ease ofdiscussion, this second signal will often also be designated as “Fiber2”, and drawn as a separate fiber, regardless of if the second signal isactually being sent on a second fiber, or simply on a second wavelengthon the first fiber.

The system will also usually have one or more remote CMRTS fiber node(s)located at the second end(s) of the first optical fiber. (Here the term“second end(s)” will also be used to designate the distal (furthest awayfrom the CMTS and the cable plant) end of an optical fiber, even aftersplitting.)

One optional component of the CMRTS fiber node(s) may be a first “dumb”optical to RF (radio frequency) conversion device that directly convertsthe first optical signals (sent as QAM waveforms by the CMTS at thefirst end of the fiber) to a first set of RF signals. These aretypically designated as O/E or E/O converters, depending upon thedirection of the electrical RF to fiber optic conversion.

Another component this CMRTS may be least one RF modulator, such as aQAM modulator device capable of detecting and encoding selected portionsof the second optical signals into a second set of RF QAM waveforms.This RF modulator may be part of a CMRTS PHY unit, and the CMRTS mayoften have the corresponding MAC and packet switching capability, aswell as an optional controller (e.g. microprocessor and associatedsoftware) to select portions of the second optical signals and controlthe packet switching, MAC and PHY (including the CMRTS QAM modulators)as needed.

As previously, discussed, in a preferred embodiment, the CMRTS PHY unitand MAC unit for this RF modulator/transmitter will be based on FPGA andDSP components, and the CMRTS will often be further designed so thatthese FPGA and DSP components can be configured by data and signalscarried by the first or second communications channel, such as opticalfiber, thus enabling the RF modulation capability of the CMRTS units tobe radically reconfigured even after being installed in the field.

The CMRTS will also usually contain at least one software controllableswitch, often different from the FPGA and DSP components, that can beremotely directed to select at least some of the second optical signals(selected second optical signals) and direct said at least one CMRTS QAMmodulator device to encode the selected second optical signals into asecond set of RF QAM waveforms at a selected set of frequencies(remotely generated QAM signals). Often this software controllableswitch will be part of, or be controlled by, the optional controller.

The CMRTS may also contain at least one remotely software controllableRF packet processor capable of detecting upstream data carried by CATVRF upstream signals generated by at least one cable modem, and digitallyrepackaging and said upstream data and retransmitting said upstream dataas a third upstream digital optical fiber signal.

Also as previously, discussed, in a preferred embodiment, the CMRTS PHYunit and MAC unit for this software controllable RF packet processor(receiver) will also be based on FPGA and DSP components, and the CMRTSwill often be further designed so that these FPGA and DSP components canbe configured by data and signals carried by the first or secondcommunications channel, such as optical fiber, thus enabling the RFpacket processing capability of the CMRTS units to be radicallyreconfigured even after being installed in the field.

Usually the software controllable switch(s) and/or software controllableRF packet processor(s) are capable of being remotely configured bysoftware to implement at least a subset of the standard DOCSIS upstreamand downstream functions. For example, on the upstream side, one or moreof the DOCSIS upstream Time Division Multiple Access (TDMA) and DOCSISSynchronous Code Division Multiple Access (SCDMA) functions may beimplemented. On the downstream side, one or more of the various DOCSISQAM modulation modes, such as 16-level, 32-level, 64-level, 128-level,and 256-level QAM modulation modes may be implemented. Depending uponthe level of functionality of the CMRTS that is desired, the CMRTS may,at the fiber node, generate QAM channels carrying digital broadcastvideo, digital video on demand, digital High Definition (HD) video,Voice data, and DOCSIS (data) channels.

In still other embodiments, additional functions that are not yetofficially part of the DOCSIS specification (i.e. non-DOCSISfunctionality), such as upstream data from various new models ofnon-DOCSIS standard set-top box gateways, may also be implemented by theCMRTS. This can be easily accomplished by uploading the appropriateconfiguration data and programs to the CMRTS FPGA and DSP units thatcomprise the CMRTS MAC and PHY. This would enable a cable provider todistinguish itself by being able to provide cutting edge services aheadof its competitors. In this example, the CMRTS can be viewed as handlinga superset of the DOCSIS functions, because it is being used to extendthe functionality of the HFC system beyond that of the standard DOCSIS3.0 functions. Here, as previously discussed, the term “superset” isbeing used to denote the additional (non-standard DOCSIS) functionality.Thus again, a CMRTS that does either a full set of DOCSIS functions or asubset of DOCSIS functions would be described as implementing a DOCSIS“superset” if it also implements additional non-standard DOCSISfunctions. Other examples of additional non-standard DOCSISfunctionality (non-DOCSIS functionality) includes functionality totransmit various forms of digital video such as standard digital video,high definition HD digital video, and various forms of digital videoupon demand.

In addition to the FPGA and DSP components, both the softwarecontrollable switch(s) and software controllable RF packet processor(s)will often incorporate their own microprocessors or microcontrollers, aswell as memory (such as flash memory, ROM, RAM, or other memory storagedevices) to incorporate software needed to operate the switches andprocessors, interpret command packets sent from the virtual shelfmanager, and transmit data packets to the virtual shelf manager.

The CMRTS will also often have a combiner device, or at least beattached to a combiner device (such as a Diplex device), that combinesthe first set of RF signals and the remotely generated QAM signals toproduce a combined RF signal suitable for injection into a CATV cableconnected to at least one cable modem. Alternatively, this Diplex devicemay be external to the actual CMRTS unit, however the CMRTS unit willnormally depend upon either an internal or external combiner (e.g. aDiplex device) for functionality.

The system will also usually have a centralized computer system orcomputer processor running software (e.g. virtual shelf software) thatcontrols many aspects of its function. As previously discussed, becausethe prior art non-dispersed functionally CMTS units were often referredto as a “shelf”, the computer software that controls the functionalityof the dispersed CMTS-CMRTS units of this invention will be referred toin the alternative as a “virtual shelf”. This “virtual shelf” softwarewill ideally manage the much higher complexity of the dispersedCMTS-CMRTS system in a way that will be easy to manage, and ideallysometimes almost transparent, to the cable plant, so that other systemsin the cable plant can often handle the more complex data distributionproperties of the invention's dispersed CMTS-CMRTS system as if thesystem behaved more like a simpler, prior art, CMTS system.

In particular, one important function of the computer processor and“virtual shelf” software will be to select and control at least thesecond optical signals and the remotely generated QAM signals. Thesewill be managed in a way that, as will be discussed, greatly increasesthe amount of IP-on-demand data available for cable system users.

Often, another important function of the computer processor and “virtualshelf” software will be to store the software and data used to configurethe various FPGA and DSP components in the various CMRTS units in thefield. Often the “virtual shelf” software, working with appropriatefeedback signals from the field CMRTS units and other devices, willoften determine when certain CMRTS units may need to be upgraded by, forexample, loading appropriate FPGA and DSP configuration data to theremote CMRTS to do pre-distortion or equalization to cope with cableimpairments on various stretches of CATV cable. In addition, often asthe human managers of the CATV system may dictate, the “virtual shelf”software may be used to upgrade (or sometimes downgrade) various CMRTSunits to add or subtract additional functionality as the user payments,user demand, and competitive situation dictate.

Thus in one embodiment, the invention may be a remote CMTS fiber node(CMRTS) system for a Hybrid Fiber Cable (HFC) network. This CMRTSportion of this system will optionally comprise a first optical to RF(radio frequency) conversion device that directly converts a first setof RF modulated optical fiber signals to a first set of CATV RF signals.The CMRTS portion will also often comprise at least one RF modulatordevice, such as a QAM modulator capable of encoding selected portions ofdigitally encoded second optical fiber signals into a second set of RFwaveforms. The CMRTs portion will also often comprise at least onesoftware controllable switch that can be remotely directed to select atleast some of the second optical fiber signals (selected second opticalsignals) and direct the at least one RF modulator device to encodecertain selected second optical signals into a second set of RFwaveforms at a selected set of frequencies. These will be calledremotely generated RF signals. The CMRTS portion will also oftencomprise at least one remotely software controllable RF packet processor(and associated MAC and PHY units) capable of detecting upstream datacarried by CATV RF upstream signals generated by at least one cablemodem, digitally repackaging this upstream data and then retransmittingthis upstream data back (often eventually usually back to the cableplant) as a third upstream digital optical fiber signal.

In a preferred embodiment, the at least one software controllable RFmodulator device and/or software controllable RF packet processor willcomprise at least one FPGA and DSP device(s) that are capable of beingremotely configured by software to implement various types of MAC andPHY units. At least some of these MAC and PHY units may be capable ofimplementing additional non-DOCSIS functionality, a full set of DOCSISfunctionality, or a subset of the standard DOCSIS upstream anddownstream functions.

Note that to enable an enhanced user data experience, the CMRTS need notimplement a full set of standard DOCSIS functionality. This is becauseat least some of the DOCSIS functionality that is ultimately deliveredto the various cable modems on the various houses will be delivered bythe directly converted CATV RF signals obtained from the CMTS at thecable plant.

In many embodiments of the invention, the functioning of the at leastone software controllable switch and the functioning of said at leastone remotely software controllable RF packet processor are preferablycontrolled a remote virtual shelf manager system.

In another embodiment, the invention may be a system and/or method forenhancing the data carrying capacity of a hybrid fiber cable (HFC)network with a cable head, an optical fiber network, a plurality ofoptical fiber nodes, a plurality of individual CATV cables connected tosaid plurality of optical fiber nodes, and a plurality of individualcable modems, each with differing data requirements, connected each ofsaid individual CATV cables. This method will usually includetransporting a first set of data from the cable head to the opticalfiber nodes using a plurality of RF waveforms, such as QAM RF waveforms,that are capable of being directly injected into individual CATV cablesby an optical to RF converter.

The method will also usually include transporting a second set of datafrom the cable head to the optical fiber nodes. Here, this second set ofdata will usually not be capable of being directly injected intoindividual CATV cables by an optical to RF converter. Rather, the methodwill instead usually convert a selected portion of this second set ofdata into RF waveforms (e.g. RF QAM waveforms) at the optical fibernodes. These remotely produced RF waveforms from selected portions ofthe second set of data will be called second RF waveforms.

In some embodiments, the method will then combine the first RF waveformswith the second RF waveforms, and inject the combined RF waveforms intoindividual CATV cables serving individual neighborhoods.

The method may control this selection and mixing process so that foreach individual CATV cable (which may be a part of a group or pluralitycontaining a number of other individual CATV cables), the first RFwaveforms and the second RF waveforms will be selected so that thecombined RF waveforms do not exceed the available bandwidth any of theindividual CATV cables.

Here, the method will often control the second set of data and theselected portion of the second set of data to satisfy (usually bettersatisfy than prior art methods) the differing data requirements for anumber of different of cable modems. Here, in general, differentindividual CATV cables, when considered in contrast to a group ofmultiple individual CATV cables, will generally carry differing secondRF waveforms, where each differing RF waveform will generally satisfythe unique data requirements for the various cable modems hooked up tothe particular individual CATV cable.

FIG. 1 shows an overall view of the various frequencies and datachannels allocated for CATV (100). Typically the lower frequencies, suchas 5-42 MHz, are allocated for use in transmitting data “upstream” fromthe individual cable modems back to the Cable Head or Cable plant (102).Typically upstream data is transmitted using a time-share TDMA (TimeDivision Multiple Access) manner in which individual cable modems areallocated certain times on roughly 2 MHz wide QAM channels to transmitdata. Starting at around 54 MHz on up to roughly 547 MHz, space iscurrently allocated for legacy analog video channels (104), whichtransmit on roughly 6 MHz wide FDM channels. At frequencies above that,frequencies (space, bandwidth) is currently allocated for digitaltelevision transmitting on roughly 6 MHz wide QAM channels (106), andabove that, space is currently allocated for DOCSIS services (108) thatmay transmit voice, on-demand video, IP, and other information, againgenerally as a series of 6 MHz wide QAM channels. Above about 1 GHz,cable bandwidth is seldom used at present. Note however, that by usingCMRTS units composed of FPGA and DSP MAC and PHY units, in conjunctionwith the methods discussed in copending application Ser. No. 13/467,709,the contents of which are incorporated herein by reference, the teachingof the present invention may also be used to extend CATV functionalityto the 1 GHz+frequency region.

The invention is indifferent as to the use of higher frequency cablebandwidth and channels. If available, the invention may use them. If notavailable, the invention will cope with existing cable frequencies andbandwidth.

CATV cable thus has a finite bandwidth of at most about 100-200 QAMchannels. When this bandwidth is used to serve a large amount ofdifferent customized types of data to a large amount of differentsubscribers, this bandwidth quickly becomes exhausted.

A drawing showing how the CATV spectrum allocation can be described in amore simplified diagram is shown below (110), (120). This diagram willbe used in various figures to more clearly show some of the CATVspectrum allocation aspects of the invention.

The “upstream” segment (112) is an abstraction of all upstream channels,including both presently used upstream channels in the 5-42 MHz region,as well as present and future higher frequency upstream DOCSIS channels.The “video” segment (114) is an abstraction of both the almost obsoleteanalog TV FDM channels, as well as the standard “digital video”channels, as well as the projected digital video channels that willoccupy the soon to be reclaimed analog bandwidths once the analogchannels are phased out. Segment (114) also represents other standarddigital radio and FM channels, and in general may represent anystandardized set of downstream channels that will usually not becustomized between different sets of users and neighborhoods.

The “DOC1” channel (116) may be (depending upon mode of use) either afull set or subset of present or future DOCSIS channels. As commonlyused in this specification, DOC1 often represents a basic set of DOCSISservices that would be made available for fallback use by neighborhoodsin the event of a failure of the higher performance IP/on demand or DOC2channels (118). The DOC1 QAM channels are normally chosen so as to notexhaust the full bandwidth of the CATV cable, so that at least someremaining QAM channels are available for the neighborhood customizedDOC2 channels. The “IP/On-demand or DOC2” channel (118) is essentially(depending upon mode of use) the remaining available downstreambandwidth on the CATV cable, and is usually reserved for transmittingneighborhood specific data (IP/On-demand data), often transported by adifferent communications media (such as a second fiber or secondwavelength, and often by a non-QAM protocol) from the cable head toindividual neighborhoods.

Note that when discussing prior art usage, the sum of the DOC1 (116) andIP/On demand (118) channels sent by optical fiber to a group ofneighborhoods can never exceed the effective bandwidth (i.e. thecarrying ability of the CATV cable and the ability of cable modems todetect the cable RF signal) of the CATV cable.

By contrast, when discussing the invention, the sum of the DOC1 (116)and IP/On-demand (118) channels sent by optical fiber to a group ofneighborhoods will often exceed the effective bandwidth of the CATVcable on a group of neighborhoods basis, although the sum of DOC1 (116)and IP/On-demand (118) will never exceed the effective bandwidth of theCATV cable on a per-neighborhood basis.

If the same CATV spectrum is transmitted by optical methods (i.e.optical fiber), so that the same waveforms are transmitted at the samefrequency spacing, but simply transposed to optical wavelengths, thenthis spectrum will be designated as (120), but the various waveformswill otherwise keep the same nomenclature to minimize confusion.

FIG. 2 shows a simplified version of how prior art HFC systems (200)transmit data from the cable plant or cable head (202) to differentoptical fiber nodes (204) serving different neighborhoods (206). Eachneighborhood will typically consist of up to several hundred differenthouses, apartments, offices or stores (208) (here referred togenerically as “houses”), each equipped with their own cable modems (notshown). Here, for simplicity, only the downstream portion of the HFCsystem is shown.

The cable plant will obtain standardized media content (210) (such as astandard assortment of analog and digital video channels) from one setof sources, and also obtain more individualized data (212), such asvideo on demand, IP from the Internet, and other individualized datafrom other sources. This data is compiled into a large number ofdifferent QAM (and at present also FDM) modulated CATV broadcastchannels at the CTMS shelf (214). This CMTS (214) will often have anumber of different blade-like line cards (216). These line cardstransmit the signals by optical fibers (218) to different areas (groupsof neighborhoods).

Note that the FDM modulated CATV broadcast signal is an analog signal(for older style analog televisions), and even the QAM signal, althoughit carries digitally encoded information, is itself an analog signal aswell. For historical reasons, in the downstream direction, both FDM andQAM waveforms (signals) usually have a bandwidth of about 6 MHz in theUS.

To show this, as previously discussed in FIG. 1, the FDM and QAM signalsare shown as having a center wavelength and bandwidth in order toemphasize the essentially analog nature of this signal, even whencarrying digital information. These analog signals can be carried byoptical fibers, and converted into RF signals for the CATV cable part ofthe network, using very simple and inexpensive equipment.

As previously discussed, typical HFC networks actually have a rathercomplex topology. Rather than sending one optical fiber from the CTMS toeach different neighborhood, typically optical fibers will servemultiple neighborhoods. To do this, the signal from the CTMS sideoptical fiber will at least usually be split (by an optical fibersplitter (220)) into several different optical sub-fibers (222), andeach sub-fiber in turn will in turn carry the signal to a differentfiber optic node (fiber node, FN) (204). Here the rather complex ringtopology of HFC networks will be simplified and instead represented bythese fiber splitters.

At the fiber node (FN) (204), the optical signal is converted into aCATV radio frequency (RF) signal and sent via CATV cables (226) toindividual cable modems at individual houses (208) in each neighborhood.Typically each neighborhood will consist of 25 to several hundredhouses, served by a CATV cable (226) that connects to the local fibernode (204).

Since the CATV cable (226) is connected to all of the houses (208) inthe neighborhood (206), if the cable modem in one house in aneighborhood wants to request customized on-demand video or IP, then allof the houses in the neighborhood that are attached to that particularCATV cable will actually receive the customized signal. Although onlythe cable modem associated with the requesting house (not shown) willactually tune into and decode the requested signal, it should beappreciated that if each individual house in the neighborhood were tosimultaneously request its own customized set of video on demand or IPat the same time, the limited bandwidth of the CATV cable would berapidly saturated. As a result, there is an upper end to the amount ofcustomized data that can be transmitted to each house, beyond whichbandwidth must be limited and/or requests for additional customized datawill have to be denied.

Although the different blades or line cards (216) of the CMTS shelf(214) at the cable plant (202) can send different customizedIP/on-demand channels to different groups of neighborhoods, thegranularity of this process is sub-optimal, because all individualneighborhoods connected to the same fiber splitter will get the samecustomized IP/on-demand signal. Given the limited bandwidth of the CATVcable, if all neighborhoods get the same signal, then the amount of datathat can be sent to each individual neighborhood must, by necessity, belimited so as not to exceed the total available bandwidth.

FIG. 3 contrasts the conversion process between the optical fiber (222)and the CATV cable (226) that occurs with a typical prior art fiber node(204), with the invention's improved CMRTS fiber node (300). Here, forsimplicity, only the downstream portion of the process is illustrated.

In the prior art conversion process (top), the optical fiber (218)carries both the standardized video signals, and the analog QAM signal(that contains digital information) for both digital television andDOCSIS use (that can carry on demand video or IP data).

In the prior art “dumb” fiber node (204) simply converts the opticalfiber's optical FDM or QAM analog signals into RF FDM or QAM signals andpasses these signals to the CATV cable (226). Thus if, for example,there are four different optical fibers connecting to this differentfiber node, all will get the same customized IP/On-demand signal, andthis in turn may be rather inefficiently transmitted to potentiallythousands of non-target households that did not request the customizedsignal.

By contrast, by using the invention's improved “smart” CMRTS fiber nodes(300), the standardized signal (e.g. the standardized video channels)and (for backwards compatibility) either a full set or subset of theDOCSIS QAM channels can be carried by the “main” optical fiber channel,here designated as “Fiber 1”, and drawn as a thicker line. For backwardscompatibility, Fiber 1 can often be the same fiber used to carry theprior-art signals, and to emphasize this backwards compatibility aspectof the invention, Fiber 1 will be designated by the same number (222).

Typically, Fiber 1 (222) will carry the CATV spectrum as a series ofoptical waveforms that directly correspond to the RF QAM waveforms thatwill be injected into the CATV cable (120).

In the invention, however, either a subset, full set, or superset of theDOCSIS QAM channels or other type RF modulated signals can also becarried by other physical media means, such as by a second fiber, or byan alternate wavelength of light on the Fiber 1. For simplicity, themedia that carries this additional set of data will be designated as“Fiber 2”, and will be drawn as a thinner line (302) to emphasize that,at least in the initial stages, Fiber 2 may be used to carrysupplemental data to extend the data carrying capability of the backwardcompatible Fiber 1 line (222). Eventually of course, Fiber 2 may likelycarry substantially more data than Fiber 1.

Although Fiber 2 (302) could also transmit its data by optical QAMwaveforms suitable for simple conversion to the RF QAM waveforms used onthe cable (by perhaps just QAM modulating the same signal at a differentfrequency), there is no requirement that Fiber 2 in-fact use any type ofQAM encoding at all. Often, Fiber 2 may transmit this supplemental databy standard gigabit Ethernet protocols. To emphasize the fact that Fiber2 is often carrying data by non-CATV-compatible or QAM signal carryingmethods, the Fiber 2 signal (304) is shown as a series of lines (306) tosymbolize the fact, that for example, alternative digital methods ofsignal transmission may be used. Here each line represents the data thatultimately will be converted to a QAM signal and sent to a specificneighborhood.

As will be discussed, in some embodiments, such as a system composedentirely of “smart” CMRTS fiber nodes (300), Fiber 1 (222) need notcarry any customized (user specific) information, such as DOCSISinformation (116), or IP/on-demand channels (118), at all. Thesecustomized channels can either be removed from Fiber 1 (222) (i.e. byfiltering) or more usually, some or all of the customized IP/on-demandchannels/DOCSIS will simply not be injected into Fiber 1 by the cableplant CMTS in the first place.

Alternatively, Fiber 1 (222) may carry the standardized video channels(114), and some of the customized DOCSIS (116) or IP/On-demand-DOCSISinformation (118), and this partial set of IP/On-demand-DOCSISinformation can be sent to those users that are still being served byprior-art “dumb” fiber nodes. The users served by the invention'simproved CMRTS fiber nodes, however will be able to access theadditional information sent by optical fiber 2, GigE, or Fiberwavelength 2 (304).

At the invention's improved CMRTS fiber node (300), the fiber node'sCMRTS unit will determine (or at least select) which set of customizeddata (308), (310), (312) its particular neighborhood requested, andretrieve this information from the Fiber 2 media (302). This informationwill then be QAM modulated and converted to the appropriate RFfrequency, put onto a suitable empty IP/On-demand QAM CATV cable channel(314), (316), (318), and then sent by CATV cable to the neighborhoodthat requested that particular data. At the neighborhood, the particularcable modem from the house that requested that data can tune into thisQAM channel and extract the data, while the other cable modems alsoattached to that cable will ignore the QAM channel and/or ignore thedata.

As will be discussed shortly, this method allows for much finergranularity, and a correspondingly higher rate of transmission ofcustomized data.

FIG. 4 shows that the invention may use a similar system and method totransmit a higher amount of data upstream as well. As previouslydiscussed, only a limited amount of bandwidth (112) is allocated totransmit data upstream from the individual cable modems in aneighborhood back to the cable plant or cable head. In this example, thelimited region from 5-42 MHz is shown (112). In the prior art process,signals from multiple different fibers would be consolidated onto asingle fiber (222), again raising congestion issues. By contrast, usingthe improved CMRTS fiber node (300), the upstream data from eachneighborhood (400), (402), (404) can be extracted, the QAM signaloptionally decoded, the data put on an appropriate (empty) returnchannel (or an empty TDMA time slice of an appropriate return channel)(406), (408) (410), and sent back to the cable head or cable plant by aless congested second customized data transmission media, such as Fiber2 (302).

Alternatively, to preserve backward compatibility, prior art upstreammethods may continue to be used. As yet another alternative, the newmethod and the prior art method may be used interchangeably by the cablesystem as system configurations and needs dictate. Here, due to theunique remote reconfigurability of the invention's FPGA and DSP MAC andPHY units in the CMRTS units, the various CMRTS units can be remotelyupgraded to implement new methods according to the wishes of the cablesystem management.

FIG. 5 shows an example of the previously discussed second option inwhich both the distribution of RF QAM channels produced by the CMTS, andthe distribution of QAM channels produced by the CMRTS, are managedtogether in a more sophisticated system employing both CMRTS and a newtype of higher functionality CMTS.

Here, in this embodiment, the improved “smart” CMRTS fiber node (300)can transport a higher effective amount of customized user data. Herethese improved “smart” CMRTS fiber nodes (300) are shown working inconjunction with an improved CMTS shelf (500) and improved CMTS linecards (502) at the cable head.

In the prior art system example previously shown in FIG. 2, an opticalfiber (218) from the prior art CMTS unit (214) at the cable plant wassplit at by a fiber splitter (220) into three sub-optical fibers (allcarrying the same data) (222), and these sub-optical fibers were thenrouted to three different neighborhoods. Because all optical fiberscoming from the fiber splitter will carry the same data, the customizeddata is inefficiently sent to all three neighborhoods, even though onlyone house from one neighborhood may have actually requested thecustomized data.

As a result, the limited carrying capacity (bandwidth) of the CATVcustomized IP/video on-demand channels can become saturated.

By contrast, by using an improved CMTS shelf (500) and improved CMTSline cards (502) capable of taking the incoming data, and partitioningthe data into two transport media (e.g. optical fibers 1 (218) andun-split optical fiber (301)). The “smart” CMRTS fiber nodes (300) ofthe invention (usually after splitter (220) further splits optical fiber1 and optical fiber 2 into sub-fibers (222), (302)) can now convey amuch higher amount of data.

As previously discussed, more data can be communicated because at eachdifferent CMRTS fiber node (300), the different CMRTS fiber nodes cancustomize and optimize the DOCSIS or other signals to and from the cableserving that particular neighborhood to better serve that neighborhood,and do so in a way that is much less constrained by overall cablebandwidth.

Here, assume that the improved CMTS (500) and improved CMTS line cards(502) have placed the appropriate data onto Fiber 1 (218) (222) andFiber 2 (301) (302). (This aspect will be discussed shortly.)

To do this, the “smart” CMRTS fiber node (300) retrieves additional data(304) from Fiber 2 (302); QAM modulates this additional data, and putsit onto a suitable empty QAM CATV cable channel (118).

In FIG. 5, neighborhood 1 has requested IP/On-demand data (312). This isselected by the neighborhood 1 CMRTS (300), QAM modulated by the CMRTS,and put onto the cable (226) serving neighborhood 1 as IP/On-demandsignal or waveform (316) in the IP/On-demand channel(s) (118). Similarlyneighborhood 2 has requested IP/On-demand data (310). This is selectedby the neighborhood 2 CMRTS (300), QAM modulated by the CMRTS, and putonto the cable serving neighborhood 2 as IP/On-demand signal or waveform(318). Note that the QAM channel or frequency (318) may occupy the exactsame channel(s) (118) as signal (316). Thus more data has beentransmitted, while at the same time, the limited bandwidth of the CATVcables serving the two neighborhoods has not been exceeded.

Thus if the neighborhood served by that smart CMRTS fiber node has notrequested that data, then the empty QAM CATV cable channel (118) becomesavailable to carry alternate types of data to that neighborhood. Ratherthan filling up the limited carrying capacity of the CATV cable withunwanted QAM channels intended for other neighborhoods, the limitedcarrying capacity of the CATV cable can instead be focused on the needsof that particular neighborhood.

In FIG. 5, neighborhoods 1 and 2 are served by the invention's improved“smart” CMRTS fiber nodes (300). By contrast, neighborhood 3 is onlyserved by a prior art “dumb” fiber node (204).

In order to continue to provide a decent level of DOCSIS or othercustomized services to neighborhood 3, the Improved CMTS shelf (500) andCMTS line card (502) may elect to send at least a subset of the DOCSISQAM channels (116) (here shown as DOC1), needed by neighborhood 3.

Here this will be less efficient, because the neighborhood 3 data isalso sent to all neighborhoods by Fiber 1, along with the video data(114) generally used by all neighborhoods, and neighborhoods 1 and 2 arenot interested in this neighborhood 3 data. However this preservesneighborhood 3 service, and keeps backward compatibility intact.

In order to provide superior DOCSIS or other IP/on-demand services toneighborhood 1 and 2, the improved CMTS (500) and CMTS line cards (502)have loaded the customized data requested by neighborhoods 1 and 2 ontoFiber 2 (302) (304) (312), (310). Fiber 2 will usually be routed to allneighborhoods, and indeed may of course simply be Fiber 1 using analternative wavelength and optionally a different protocol.

As a result, the system's effective ability to deliver customized datato neighborhoods 1 and 2, served by the improved “smart” CMRTS fibernodes (300) and improved CMTS (500), (502) has substantially increased,because the IP/On-demand channels can be customized with data specificto each neighborhood. At the same time, backward compatibility ispreserved because neighborhood 3, which still uses a prior art dumbfiber node 3 (204) can continue to make use of the DOCSIS subsetchannels transmitted by Fiber 1 (222).

FIG. 6 shows additional details of how the “smart” CMRTS fiber nodes(300) may operate in conjunction with an improved cable plant of cablehead CMTS (500) and improved CMTS line cards (502). For simplicity,again primarily the downstream portion of the system is shown. The CMRTSfiber nodes (300) often will have a simple optical to electric (O/E)(600) converter to convert the main (standardized) CATV analog (FDM andQAM) data/waveforms (120) optically transmitted by Fiber 1 into an RFsignal. That is, this O/E converter is an optical to RF (radiofrequency) conversion device that directly converts a first set of RFmodulated optical fiber signals to a first set of CATV RF signals. TheCMRTS fiber nodes (300) will often also have an electric/optical (E/O)(602) converter to take the upstream RF data from the CATV cable, andconvert it to an optical signal suitable for sending back to the cablefarm by either Fiber 1 (not shown) or Fiber 2 as desired. In otherwords, this E/O converter is a RF (radio frequency) to opticalconversion device that directly converts a first set of upstream CATV RFsignals to RF modulated optical fiber signals and sends said RFmodulated optical fiber signals upstream relative to the CMRTS unit.

The CMRTS fiber node (300) will also contain a CMRTS unit (604) thatwill take the customized IP/on-demand data signal (304) from Fiber 2(301), (302), RF modulate this data (often RF QAM modulate) to anappropriate empty CATV RF QAM channel (118), and transmit thiscustomized data onto the CATV cable (226).

The RF converted main CATV analog (e.g. QAM channels) signal (114),(116) from fiber 1 (218), (222), and the frequency shifted customizedIP/on-demand QAM channel (318) from fiber 2 (301), (302), (312), arecombined (for example by using a Diplex unit (606) located either insideor outside of the CMRTS fiber node (300)), and the full reconstitutedCATV signal containing both the standard CATV video (114) and DOCSISCATV subset (116), and the extended IP/On-demand QAM modulated data(318) is then sent out to the various houses in the neighborhood usingthe CATV cable (226).

As previously discussed, it should be appreciated that since at leastinitially most HFC systems will consist of a changing mix of bothimproved CMRTS fiber nodes and older “dumb” fiber nodes; this willimpose a considerable configuration and management problem on the CMTSunit (500) at the cable plant (202). This complexity is handled by acomputerized network management system and software termed the “virtualshelf”.

In one embodiment of the improved “virtual shelf” system, the CMTS (500)and improved CMTS line cards (502) may be configured with both packetprocessors (610), and MAC (612) and PHY (614) devices or functionalityto transmit standard CATV analog, QAM, and DOCSIS signals onto the first(main) optical fiber 1. The same line cards may also be configured withpacket processors (616), MAC (618) and PHY (620) functionality totransmit supplemental IP/On-demand extended DOCSIS data on optical fiberline 2 or fiber wavelength 2. As previously discussed, the Fiber 2extended data may often be encoded by an entirely different (non-QAM)methodology (304). As a result, the MAC (618) and PHY (620) for Fiber 2can be different (e.g. follow standard GigE protocols) from the MAC(612) and PHY (614) used for Fiber 1.

The exact mix of Fiber 1 and Fiber 2 signals transmitted and received bythe improved line card will vary depending upon what sort of fiber nodesare connected downstream (southern end) to the line card (502).

For example, if all of the fiber nodes were “dumb” prior art fiber nodes(204), then the CMTS line card would only transmit on Fiber 1, and thefunctionality of that particular CMTS line card would be backwardcompatible with prior art CATV DOCSIS equipment and fiber nodes. Thatis, Fiber 1 (218), (222) would transmit the full set of DOCSIS channels,and Fiber 2 (301), (302) will transmit nothing because there are noCMRTS fiber nodes (300) available to listen to the Fiber 2 data.

By contrast, if all of the fiber nodes were “smart” improved CMRTS fibernodes (300), then the improved CMTS (500) and CMRTS line card (502)might elect to maximize all DOCISIS channels (116) and all availablecustomizable data to the various households on Fiber 2. In this case,Fiber 1 would only be used for transmitting standard video channels(114).

This alternative scheme would maximize the number of vacant QAM channelson the CATV cable, and thus allow the highest amount of customized datato be sent to the houses on that particular stretch of cable.

In a mixed “dumb” fiber node (204) and “smart” CMRTS fiber node (300)situation (as previously shown in FIG. 5), the improved CMTS (500) andCMTS line card (502) should ideally elect to transmit and receivestandard video channels (114) and a subset of DOCSIS (116) informationto and from neighborhood 3 (served by the “dumb” fiber node), usingFiber 1 to continue giving adequate service to neighborhood 3.

However to give superior performance to neighborhoods 1 and 2 (served bythe “smart” CMRTS fiber nodes (300)), the improved CMTS (500) and CMTSline card (502) should ideally keep some DOCSIS QAM channels vacant onFiber 1. The “smart” CMRTS fiber node (300), which may be instructed byoutside commands (to be discussed) will then determine or at leastselect what GigE data (304) transmitted by Fiber 2 (302) is needed byits particular neighborhood, QAM modulate it, and distribute it to itsneighborhood on the empty QAM channel. In the FIG. 6 example, data (312)has been QAM modulated and transmitted as QAM waveform or data (318).

Thus the same empty QAM channel frequency can transmit one set of datato the houses in neighborhood 1, and a different set of data to on thesame empty QAM channel frequency to the houses in neighborhood 2.

This scheme is both highly efficient and backwards compatible, howeverit imposes a significant configuration and management burden on thecable plant CMTS. This is because each time a “dumb” fiber optic node(204) is converted to a “smart” CMRTS fiber node (300), theconfiguration of the network changes.

As previously discussed, in order to manage this complexity, thefunctionality of the improved CMTS (500) and CMTS line cards (502), aswell as usually the functionality of the CMRTS fiber nodes (300), isextended by use of additional “virtual shelf” network managementcomputers, controllers, and software.

In one embodiment, a unified network management system (exemplified by,for example, the ConfD management system provided by Tail-fincorporated) is added to the improved CMTS (500) and line card (502) tounify the network and CMTS hardware and virtualization layer, provideoperating system services, manage middleware, and configure the systemto use the proper networking protocols. In this embodiment, all or atleast much network configuration data is stored on a database in theCMTS manager, and the configuration of the network is controlled by aprocess in which the management software (ConfD) communicates over IPC(sockets) with apps that control the function of various packetprocessors, MAC, and PHY devices on the improved CMTS and CMRTS units.

Here the a computer or processor and associated software memory (622)are shown directly controlling the operation of an improved CMTS unit(500) by way of various other controllers (624), (626) located in theimproved CMTS backbone (627) and line cards (502). The communicationsbetween this “virtual shelf manager” (622) and the local controllerprocessors (624), (626) are shown as dashed lines (628). The virtualshelf manager may also control the operation of a level 2/3 switch (629)and/or other devices that connect the improved CMTS unit to the mediacontent (210), Internet IP/On-demand data or “cloud” (212), and otherservices provided by the cable plant (202).

The virtual shelf manager may often also manage the configuration of thevarious “smart” CMRTS fiber nodes (300), often by communicating withcontrollers and applications software embedded with the CMRTS fibernodes (not shown). Given the typically long distances between the CMRTSfiber nodes (300) and the virtual shelf manager (622) and improved CMRT(500) (which will often be located at the cable head or cable plant,miles or more away from the various nodes (300)), the CMRTS fiber node(300) to virtual shelf manager (622) communication will often be done byvarious signals and signal protocols communicated by optical fibers 1 or2. In one preferred embodiment, socket based inter-process communication(IPC) protocols are used.

This enables the configuration of the CMTS shelf, and indeed the overallnetwork, to be rapidly reconfigured to meet the ever changing networkmodel generated by the invention. Often it will be convenient to storethis network configuration, as well as the properties of the variousnetwork devices, in a configuration database (630) and configurationdatabase memory device (not shown).

FIG. 7A shows more details of the CMRTS fiber node (300) (here shownwithout the diplex unit and/or signal combiner (606) (e.g. a diplex RFsignal combiner device) and the CMRTS unit (604). At a higher or atleast alternate level of abstraction, the CMRTS unit of the CMRTS fibernode will typically comprise a first QAM-RF packet processor (700) withMAC and PHY units that convert the downstream data on Fiber 2 to aplurality of radiofrequency (RF) QAM waveforms (channels) and outputthis data downstream (702) to the local CATV cable. As previouslydiscussed, to maintain fallback capability, the CMRTS fiber node willalso usually have an Optical to electrical converter (600) capable ofdirectly converting the CATV waveforms sent on Fiber 1 to RF CATVwaveforms suitable for injecting into cable (226)

This CMRTS unit may also optionally comprise a second RF-upstream packetprocessor (704) that will read the upstream RF signals (data) sent bycable modems connected to the local CATV cable (706), and convert thisupstream data to appropriate Ethernet or other data communicationsprotocols suitable for communicating this cable modem data back upstreamto the improved CMTS (500) at the cable head or cable plant by way ofFiber 2. This RF-upstream packet processor is optional becausealternatively (for backward compatibility) the upstream data sent by thecable modems may be returned to the CMTS by simply taking the upstreamRF signal (708), running it through an electrical to optical converter(602), and transmitting it back to the CMTS by way of Fiber 1 (222).

The operation of both packet processors (700), (704) and if desired, theO/E and E/O converters (600), (602) may be remotely controlled by thevirtual shelf manager (622) by way of suitable controllers (oftenmicroprocessors), and local applications software (Apps) that interceptdata from Fiber 1 (222) or Fiber 2 (302), and receive and send commands,often by way of a specialized communications protocol such as thepreviously discussed sockets protocol.

At a deeper level that exposes more details of the PHY units in both theQAM-RF packet processor (700) and the optional RF-upstream packetprocessor (704). The CMRTS unit (604) will normally comprise a dataswitch, such as a DOCSIS Level 2 forwarder (710), at least onecontroller (often a microprocessor and associated software, not shown),various QAM modulators (712) to take the DOCSIS data and/or otherIP/on-demand data from Fiber 2 (302) and convert, QAM modulate, andfrequency shift the data as needed to fit into suitable empty CATVchannels. To do this, CMRTS unit may employ a controllable clockgenerator (714) to control the frequency and timing of the QAM channels,as well as variable gain amplifier (VGA) units (716), (718) to help thePHY portions of the units manage the analog processes in convertingsignals back and forth between the CMRTS unit (300) and the cable RFsignals.

As before, the DOCSIS Level 2 forwarder (710) switches, and the switchesthat control the QAM modulators (712) and analog to digital (A/D) units(720) may be remotely controlled by the virtual shelf manager (622) bylocal (embedded) controllers (often microprocessors) and associatedapplications software by commands to and from the Virtual Shelfsoftware. As before, often these commands may be sent over the sameFiber 1 or Fiber 2 pathways normally used to transmit other data, andagain may use socket based inter-process communication (IPC) protocols.

As before, the return process for processing upstream data can implementthe earlier electronic to optical (E/O) converters and send the upstreamsignals back with essentially no modification other than the conversionto light wavelengths. Alternatively, the upstream process may be anupstream version of the invention's previously discussed downstreamprocesses.

In one embodiment, the variable gain amplifier (VGA) units (718) willconvert the incoming upstream RF signal from the local neighborhood CATVcable into a signal which is then tuned into and digitized by the clockgenerator and A/D converter, and then forwarded by the DOCSIS Level 2forwarder or other switch (710) towards the cable plant, often usingFiber 2 (302) so as to allow greater amount of upstream data to be sent.Here again, the DOCSIS Level 2 forwarder and conversion circuitry (710)may be controlled by commands from the Virtual Shelf software.

FIG. 7B shows additional details of CMRTS fiber nodes employing FPGA andDSP based MAC and PHY units, here configured to reproduce the samefunctionality as previously shown in FIG. 7A. Here DSP (740) and theFPGA (742) devices implement the functionality of the MAC and PNY unitsof the DOCSIS Level 2 Forwarder (710) and QAM modulator (712). Dependingon the FPGA used, other functions, such as the A/D and D/A converters,may either be implemented by the FPGA or by other devices external tothe FPGA. In some embodiments, to be described, the FPGA (742) can beconfigured to implement a filter bank type RF QAM modulator to replacethe functions of QAM modulator (712). Here again depending on thecharacteristics of the FPGA used, the FPGA output may be furtherprocessed through a D/A converter (744) and power amplifier (746) toproduce RF modulated signals (here QAM RF signals) of sufficient powerlevels for the CATV cable (226).

Program and data memory for the DSP can be stored in computer memorysuch as Flash and DRAM memory, shown as (748) and (750) respectively.

FIG. 8 shows more details of how the virtual shelf manager (622) and theconfiguration database (630) (previously shown in FIG. 6) may controlthe functionality of most or all of the plurality of CMRTS fiber nodes(300), improved CMTSs (500) and CMTS line cards (502), and optionallyother active nodes and switches in the HFC network system.

In this example, the virtual shelf manager software (622) is shownrunning as a module of a broader CMTS manager software package (800);however it also may be run as a standalone package. The CMTS managersoftware (800), which will often be run on one or more computerprocessors which may be located at the cable plant or other convenientlocation, will often be based on network configuration managementsoftware (802). Such network configuration software (802) (also calledthe Operational Support Systems (OSS) software) may be, for example,software based upon the ConfD network management software produced byTail-f Systems Corporation, Stockholm Sweden (International location)and Round Hill Virginia (US location).

In this embodiment, use of software such as ConfD is useful because thistype of network management software also provides a number of convenientand commonly used interfaces to allow users to interact with the networkand control then network configuration. These interfaces may includeNETCONF management agents, SNMP agents, Command Line Interfaces (CLI),Internet (Web) interfaces, and other agents/interfaces as desired.

The virtual CMTS shelf software that may be used to control the statusof the various CMTS line cards (502) and CMRTS fiber nodes (300) willoften interact with a network configuration database (630) run under thecontrol of this network configuration software (802). The virtual CMTSshelf software will in turn send commands out to most or all of thevarious remote CMRTS fiber nodes, as well as control the operation ofthe CMTS (500) at the cable head (cable plant), and other devices asdesired. As previously discussed, one preferred way for this control tobe achieved is by way of socket based inter-process communication (IPC)protocols and packets (804), which may be sent over the samecommunications lines used to send the CATV and DOCSIS data, such as theFiber 1 (218) and Fiber 2 lines (302). In this situation, for example,controllers running various types of application software (Apps) in theplurality of remote packet processors (700), (704) in the remote CMRTSfiber nodes (300) can listen for appropriate commands from the virtualshelf manager (622), and adjust the operation of the CMRTS packet (700),(704) processors accordingly. These CMRTS fiber nodes can also transmittheir status back to the virtual shelf manager using the same protocols.

The device configuration database (630) of the virtual shelf managersystem will often have multiple data fields, including fields thatcontain the identification code and/or addresses of the various CMRTSunits in the network (CMRTS identifier fields). The database will alsousually have information on the status of the various cable modemsconnected to the various CMRTS units, including the cable modemidentification data (cable modem identification data fields) and theprivileges of the various users that are associated these various cablemodems. For example, one user may have privileges to access a broadarray of services high bandwidth upload and download data, while anotheruser may have limited access to a different set of services and morelimited upload and download data privileges. Other functions that may beimplemented include event logging, Authentication, Authorization andAccounting (AAA) support, DOCSIS Management Information BASE (MIBs)functions, etc.

Other fields that normally will be in the database will includeinformation as to user identification fields (user privilege fields),available DOCSIS channels, available IP addresses, instructions for howto remotely configure the various CMRTS software controllable switches,and instructions for how to remotely configure the various CMRTSsoftware controllable RF packet processors.

The Virtual shelf manager and configuration database, as well as othercomponents of the system, will usually be run on a computer system withat least one microprocessor, as well as standard hardware and software,such as MAC and PHY units, that will enable the virtual shelf manager tosend and receive data packets (often through the IPC protocol) to thevarious remote CMRTS units on the network.

The OSS software (802) can inform the virtual shelf manager softwareabout the privileges, certificates, and encryption keys assigned to thevarious users. The OSS can also set policies or allocation limitsregarding the frequency and bandwidth that will be assigned to thevarious channels. The OSS can also respond to queries from the virtualshelf manager when new modems are detected. The OSS can further takestatistical data collected by the virtual shelf manager, such as packetstransmitted and received, volume of data, and use this information forbilling and network management purposes.

Further information on OSS functions, and more examples of functionsthat may be implemented in the OSS software for the invention, may befound in Misra, “OSS for Telecom Networks: An Introduction to NetworkManagement”, Springer (2004).

For example how this system would operate, consider the case where a newcable modem is first connected to the system. The cable modem will sendan upstream DOCSIS signal (226) to the CMRTS (604). The RF-up packetprocessor (704) in the CMRTS (604) will in turn collect the informationrelating to the cable modem identification number, and other relevantparameters, repackage the data in a digital format, and send it backupstream to the virtual shelf manager system on the fiber GigE link(302). The virtual shelf manager system (622) will looks up the cablemodem identification data in the device configuration database (630),and determines the privileges of the user associated with said cablemodem identification data, and depending upon the value of the userprivilege field, available DOCSIS channels, and available IP addresses,sends data packets to the CMRTS (700) unit, often by way of the IPCprotocol (804) that controls that particular cable modem.

These data packets will interact with applications (e.g. App 1, App n)and configure the software controllable switch(s) on the CMRTS unit(700), to configure the software controllable switches on the QAM-RFpacket processor (700) and the cable modem available IP addresses so astransmit downstream data to the cable modem on a first available DOCSISchannel. The data packets will also configure the software controllableRF packet processor (704) to receive upstream data from the cable modemon a second available DOCSIS upstream channel and IP address andretransmit the upstream data as a third upstream digital optical fibersignal (302).

Often the virtual shelf manager (622) will handle IP addresses for thecable modems through the proxy Dynamic Host Configuration Protocol(DHCP) service, or other method.

As also discussed elsewhere, one particular advantage of this approachis its excellent forward and backward compatibility. The same CMRTSunits can be used in present HFC networks, HFC networks usingconventional CMTS units (option one), or advanced HFC networks usingadvanced CMTS units (option two).

As an example of the advanced CMTS option two system in operation,suppose that as a result of routine maintenance, the “Dumb” fiber node 3(204) from FIG. 5 is now replaced by a “smart” CMRTS fiber node 3 (300).As a result of this change, the network may wish to optimize theperformance of this branch of the network by, for example, nowconfiguring the CMTS line card (502) that sends a signal to Fibersplitter “n” (220) to now stop sending the DOC1 (116) channel on Fiber 1(218), (222). By no longer transmitting the DOC1 channel on Fiber 1,additional empty channels (frequencies) are created on this branch ofthe HFC network that instead can be used to transmit additionalIP/On-demand data by way of Fiber 2 (301), (302).

In order to accomplish this change, the virtual shelf manager (622) willsend commands to the appropriate Level 2/3 switch (629) and CMTS linecard (502) reconfiguring the CATV Video and DOCSIS packet processor(610), CATV MAC (612), and CATV PHY (614) to no longer transmit the DOC1 channel. The virtual shelf manager will also send commands to theappropriate Level 2/3 switch (629); GigE (Gigabyte Ethernet) packetprocessor (616), the GigE MAC (618), and the GigE PHY (620), toalternatively send the data that normally would have been transmitted bythe DOC 1 channel on Fiber 1 (218) to now transmit this data by Fiber 2(301). The virtual shelf manager will also communicate with CMRTS fibernodes 1, 2, and new CMRTS fiber node 3 (300) instructing the fiber nodesto look for the former DOC1 data on Fiber 2 (302) using the QAM-RFpacket processor (700) and/or the DOCSIS L2 forwarder (710) and use QAMmodulator (712) to QAM modulate this DOC1 data, and send the data out onthe empty DOC1 channel (116). The virtual shelf manager can now makebetter use of this formerly inefficiently used DOC1 channel (frequency)because now it is used to send neighborhood specific data.

Here the improvement in flexibility increases the amount of dataavailable to the system's users. Under the prior art system the DOC1 QAMsignal on the Doc1 channel (frequency) (116) was transmitted to allthree fiber nodes to the cables in three different neighborhoods,regardless of if any cable modems hooked to CATV cable attached to aparticular fiber node needed the data or not. Now, by replacing “dumb”fiber node 3 (204) with “smart” CMRTS fiber node 3 (300), the ability ofthe other neighborhoods to receive a broader array of customizedIP/On-demand services has been increased.

Continuing with this example, further suppose that the CMRTS unit (604)in new CMRTS fiber node 3 (300) experiences an early mortality failuresoon after installation. In this case, the 0/E and E/O portions (600),(602) of CMRTS fiber node 3 will continue to operate, and as a result,the failed CMRTS fiber node 3 (300) now acts like “dumb” fiber node 3(204) again. In this case, the virtual shelf manager (622) can cope withthis failure by simply rolling back the changes that it just made, andservice to all three neighborhoods can continue (at the less capableprior level) while the failed new CMRTS fiber node 3 is serviced.

The data and software needed to configure the FPGA and DSP devices forthe CMRTS MAC and PNY units (configuration data) can be stored in morethan one place. In some embodiments, this configuration data can bestored in memory (i.e. RAM, ROM, Flash memory, etc.), such as FIG. 7B(748) onboard the remote CMRTS units. Indeed configuration data for morethan one FPGA and DSP configuration may by be so stored, and the CMRTSunits may be equipped with some capability to self-configure dependingon local circumstances. Alternatively or additionally, however, theconfiguration data will often be stored outside of the CMRTS, such as inthe remote virtual shelf manager configuration database (630) previouslydiscussed.

In this later approach, the remote virtual shelf manager (622) can thenreconfigure the CMRTS FPGA and DSP based MAC and PHY under centralcontrol, using the same type of Socket based Inter-Process Communication(IPC) (804) or other approach. The net effect of this later system isto, in effect, allow instant “field upgrades” of the CMRTS unitswhenever the managers of the system so desire. Thus for example, aupdated FPGA program or image can be downloaded from the configurationdatabase (630) to the CMRTS onboard flash memory (FIG. 7, 748), and thenused to update the configuration of the FPGA to allow for additionalCMRTS MAC and PHY hardware capability as needed. The DSP program anddata can also be updated using this method.

Thus to summarize, the CMRTS FPGA and DSP units can be reconfigured by avirtual shelf manager system, such as FIG. 8 (800) with a deviceconfiguration database (630) with at least CMRTS identifier fields,cable modem identification data fields, the privileges of usersassociated with said cable modem identification fields (user privilegefields), available DOCSIS channels, available IP addresses, instructionsto configure said at least one software controllable switch, andinstructions to configure remotely software controllable RF packetprocessor. This virtual shelf manager system will generally comprise atleast one processor; and hardware and software capable of sending andreceiving data packets to and from a plurality of remote CMRTS units(e.g. 700, 704).

The device configuration database (630) can thus additionally comprise aplurality of FPGA configuration data and DSP program data. The virtualshelf manager can download at least some of this FPGA configuration dataand/or DSP program data to various remote CMRTS fiber nodes (e.g.installed CMRTS nodes in the field, such as 700, 704) as needed.

FIG. 9 shows an example in which the invention's CMRTS system is used ina more conventional CMTS HFC system. Here the CMTS shelf is a standard(prior art) CMTS shelf (214), that has been configured by the cableoperator to leave some QAM channels (DOCSIS channels) empty. The datathat is handled by the CMRTS units (604) in the CMRTS Fiber Node (300)is handled in a manner that is completely separate from the data handledby the standard CMTS shelf (214), which is simply passed back and forthfrom the local cables (226) in the various neighborhoods by the simpleO/E (600) and E/O (602) devices in the CMRTS fiber node (300).

Here, the Internet/IP etc. data (212) destined for the various CMRTSunits (604) are handled by a Level 2/3 switch that is independent of theCMTS (214), converted to an optical signal by the GigE MAC and PHY unitsdiscussed previously (not shown), and sent along fiber 2 (301) asbefore. Here, the virtual shelf manager (622) interacts only with theLevel 2/3 switch (629) and the associated CMRTS units (300), but notdirectly with the standard CMTS shelf (214). As before, the virtualshelf manager (622) is controlled by the network configurationmanagement software (OSS) (802).

FIG. 10 shows additional details of how the “smart” CMRTS fiber nodes(300) may operate in conjunction with prior art cable head CMTS (214)and prior art CMTS line cards. As for FIG. 9, the function of the CMRTSis essentially the same, however the prior art CMTS shelf (214) will nolonger intelligently manage its QAM channels, but will instead simplyhave some pre-allocated empty QAM channels that may be filled in by theCMRTS units.

Note that although the CMRTS examples used packet processors (700),(704), in an alternative embodiment, one or more of these packetprocessors may not be needed. Alternatively the signal may be simplypassed through, or else modified by wave shaping, or modified by someother means.

As an example, still another embodiment, the CMRTS FPGA and DSP basedMAC and PHY units may be configured to not contain QAM modulators atall. In this alternative embodiment, QAM signals may be sent up and downthe second optical fiber (for example, to and from the cable plant oroptical fiber nodes closer to the cable plant), and the CMRTS FPGA andDSP units can simply implement frequency shifting circuitry to convertthe second optical fiber QAM signals to an appropriate empty CATV QAMchannel (DOCSIS channel).

FIG. 11 shows how the FPGA and DSP components of the MAC and PHY unitsof a CMRTS fiber node can be reconfigured to implement an RF filter banktransmitter, such as a RF QAM transmitter. To implement RF QAMtransmitters using FPGA and DSP devices, the methods of Harris et. al.,(“Digital Receivers and Transmitters Using Polyphase Filter Banks forWireless Communications”, IEEE Transactions on Microwave Theory andTechniques, 51(4), pages 1395-1412, 2003), or alternative methods, maybe useful. Briefly, the CMRTS MAC and PHY transmitter devices can takethe incoming bit stream data d_(0,k), d_(1,k), d_(N-2,k) and d_(N-1,k),(1100), RF modulate it by running the data through an inverse FastFourier Transform (FFT⁻¹) waveform generator (1102) implemented by theFPGA and DSP MAC and PHY units of the CMRTS, then run the signal throughpolyphase filters E₀ . . . E_(N-2) (1104) (e.g. Finite Impulse Response(FIR) filters), multiplex the result, and output through a Digital toAnalog converter producing QAM modulated RF output signals (1108) Thissystem can produce a series of stacked RF QAM channels producing an RFspectrum such as shown below (1110).

In principle, in addition to QAM modulated RF waveforms, other types ofRF waveforms, such as Code Division Multiple Access (CDMA), OrthogonalFrequency Division Multiplexing (OFDM) and indeed any type of RFmodulation scheme may also be produced by the FPGA and DSP based CMRTSMAC and PHY units.

Additionally, as previously discussed, the software configurable RFmodulator/transmitter device may be further configured to implement anRF modulator and transmitter that pre-distorts or customizes said secondset of RF waveforms to correct for RF signal impairments in at leastpart of the Cable portion of said Hybrid Fiber Cable (HFC) network.Here, as previously discussed, the methods of parent application Ser.No. 13/478,461, incorporated herein by reference, may be implementedusing the present invention's FPGA and DSP based MAC and PHY transmitterunits.

Although the stacked QAM channel RF output channels shown in (1110) areall drawn with equal magnitude, one advantage of this approach is thatin actuality, the amplitude of the different channels need not be set tobe equal. Generally in CATV cable, higher frequencies are attenuatedmore rapidly than lower frequencies. Thus here, for example, the FPGAand DSP implemented CMRTS MAC and PHY transmitter can be configured toweigh some channels (e.g. the higher frequency channels) with a higheraverage amplitude than other channels, thus giving that individual CMRTSunit the ability to cope with local CATV signal impairments. Forexample, if a given stretch of CATV cable is unusually long, with acable modem tuned to a higher frequency channel far away andexperiencing signal degradation, the CMRTS unit may be reconfigured toweigh that particular channel with a higher amplitude. Such differentialweighting intended to overcome channel impairments is calledpre-distortion, and the system can thus implement programmablepre-distortion using these methods.

FIG. 12 shows an example of the division of labor between the singlehandling steps handled by the FPGA portion (1200) and the DSP (1202)portion of the MAC and PHY units of a FPGA and DSP based CMRTS unit.Here a TDMA burst receiver implementation is shown. The lower portion ofFIG. 12 (1204) shows an example of a superhetrodyne receiverimplementation, most useful when the various upstream CATV channels arenot regularly frequency spaced. Here the methods of Harris et. al. mayalso be useful.

Here, at the digital front end, the system obtains incoming RF signalsamples, and the FPGA component (1200) (which itself is softwareconfigurable) can handle the initial stages of the Analog to Digital(A/D) conversion process. The FPGA can also tune into the signal (e.g.implement a tuner and match filter). In this configuration, the FPGAthen transfers the data to the DSP (1201) at a first data rate andformat, such at a rate of two samples per symbol. The DSP (1202) canthen implement other functions, such as a DOCSIS RF signal burstdetector (SBD) and Timing recovery (TR) function, carrier recovery (CR),equalization (Equalizer), DOCSIS demapping and descrambling functions(De-mapper, Descrambler), and Reed Solomon error correction (RS).

The descrambler here can, for example, be a standard DOCSIS descrambler.DOCSIS transmitters and receivers use scrambler and descrambler methodsto introduce enough randomness into the DOCSIS QAM RF signals as toproduce enough signal transitions for the receiver to lock on to, thusallowing the system to maintain proper synchronization.

The system may also do additional DOCSIS functions, such as headerinspection, parsing, fragmentation correction, error suppression, andthe like. As before, although RF QAM modulation methods are often usedas the main example of an RF modulation scheme throughout, the systemmay be configured to receive other non-DOCSIS RF modulation schemes suchas CDMA or OFDM modulated RF signals.

It should also be apparent that as for the CMRTS transmitter, the CMRTSsoftware controllable RF packet processor's at least one FPGA device mayalso be configured or reconfigured using FPGA configuration data that iseither stored in memory at the remote CMTS fiber node (e.g. FIG. 7A(748)), or downloaded from the configuration database FIG. 8 (638) of aremote virtual shelf manager system FIG. 8 (622), (800). Similarly theCMRTS software controllable RF packet processor's at least one DSPdevice may also be programmed using DSP software that is either storedin memory at said remote CMTS fiber node (748), or downloaded from thedatabase (638) of a remote virtual shelf manager system (622), (800).

Various types of receivers may be implemented using FPGA and DSPtechniques. One type is a superheterodyne receiver (1204), which isoften more useful when the various RF channels to be received are notregularly spaced. Here for example, the local oscillator signal of thetype such as

$^{- \frac{j\; 2\pi \; n\; k}{N}}$

is mixed with the incoming signal x(n) by multiplication, and the sumand difference of the two signals is then filtered at step h(n) using,for example, an impulse response filter. The output of this process isthen further decimated to reduce what may be initially a very highfrequency sampling rate down to a lower sampling rate, producing usefuloutput. These steps will often be implemented in the FPGA portion of thecircuit.

FIG. 13 shows how the FPGA and DSP components of the MAC and PHY unitsof a CMRTS fiber node can also be reconfigured to implement a filterbank receiver, which may be a QAM receiver. This configuration is mostuseful when the various upstream CATV channels are regularly frequencyspaced. Here again the methods of Harris et. al., or alternativemethods, may be used.

Filter bank receivers tend to be more useful when there is a series ofregularly spaced incoming RF channels to receive, as shown in FIG. 13(1300). Filter bank receivers generally function by a method that is theinverse of the filter bank transmitter previously described in FIG. 11.

In this embodiment, the CMRTS FPGA and DSP based MAC and PHY units canbe configured to implement a software controllable RF packet processorreceiver. One advantage of this approach is that it then becomesrelatively easy to further configure the various receiver(s) withcapability to equalize or adjust various CATV upstream RF signals(usually originating from various cable modems) to correct for RF signalimpairments in at least part of the cable portion of the Hybrid FiberCable (HFC) network.

FIG. 14 shows a simplified flow diagram of some of the signal flowprocessing steps required to perform other DOCSIS functions. These againare often handled by the DSP portion of the FPGA and DSP based CMRTS MACand PHY units.

Here the RF burst signals are first acquired by the FPGA. The RF burstsare then processed, the various data packets transmitted by the RFbursts detected, and these data packets in turn are parsed, reassembled,ad directed to various functions. For example, the system may inspectthe header of a data packet, determine if it is a MAC message or a datapacket that needs to be forwarded, and take appropriate action dependingon the header.

FIG. 15 shows an alternative view of the CMRTS based CATV network from asoftware management and system control perspective.

Other Embodiments

Other alternative embodiments of the invention are also possible. Inthese alternative embodiments, the CMRTS, described in more detail inU.S. provisional application 61/511,395, the contents of which areincorporated herein by reference, units can have multiple outputs, suchas multiple CATV cable outputs, or even a mix of CATV or Coax cableoutputs and, other output types such as data outputs (e.g. GigE or otherdata output), telephony outputs, and the like.

In other alternative embodiments, the CMRTS units may also be positionedmuch closer to an individual household. For example, in some alternativeembodiments, the CMRTS units may be positioned extremely close to, oreven attached to, either a multiple household unit such as an office orapartment building, or even attached to an individual household, inwhich case the CMRTS unit can act, to some extent, somewhat like a“fiber to the home” Optical Network Terminal.

FIG. 16 shows an alternative embodiment in which the CMRTS unit (1300)is configured to feed multiple electrical RF or data outputs, such asfour CATV cable outlets (1302, 1304, 1306, 1308), or alternatively a mixof CATV cable outlets and other electrical outputs, such as data ports(e.g. GigE ports) and/or telephony ports.

A diagram of one potential configuration for (1300) is shown in (1310).This configuration, where the CMRTS unit is configured to drive multipleCATV cables, may be useful when the CMRTS unit (1310) is used to drive amultiple-household facility, or where the CMRTS unit may be configuredto drive a neighborhood partitioned into multiple CATV cables (e.g. seeFIG. 6, where the CMRTS unit (1300) is essentially used as a single unitto replace both smart fiber splitter (220) and CMRTS FN 1 (300) andCMRTS FN 2 (300), and possibly even Dumb FN 3 (204)).

Here the standardized video signals, intended to be transmitted on allcables (1302, 1304, 1306, 1308), can be handled by a method common toall cables (1302, 1304, 1306, 1308), such as a simple Optical toElectrical converter (1312), and these results may go to all outputcables (1302 to 1308). Indeed, common digital video signals (1314) maybe handled by a similar mechanism. In the simplest alternative however,the different Units 1, 2, 3, and 4 (1316, 1318, 1320, 1322) can bedifferent CMRTS units (e.g. formerly 604), and may be now assigned todifferent cables (e.g. one CMRTS for cable (1302), another CMRTS forcable (1304), and so on, thus enabling this alternative D-CMRTS fibernode to now handle multiple neighborhood portions of cable, or multipleportions of cable for a single building.

In yet another and more radical alternative, however, at least units(1318), (1320), (1322) may be other types of optical to electronic datahandling units assigned to other purposes. For example, in onealternative embodiment, unit 2 (1318) may configured with the MAC andPHY capability for IP data, in which case electrical cable or interface(1304) may be a data port, such as a GigE port or other type data port.Similarly Unit 3 and/Unit 4 (1320), (1322) may be configured with theMAC and PHY capability for telephony data, in which case electricalcable or interface(s) (1306) and/or (1308) may be one or more telephonycables or interfaces, such as for a phone and/or fax line.

Thus in an extreme case, the neighborhood(s) (206) may be as little as asingle household or at least a single multiple unit facility. In thisextreme situation, the length of the CATV cable (226) may be de-minimis(i.e. extremely short), and the CMRTS unit (1300), (1310) may indeed beaffixed to the household or other facility.

FIG. 17 shows an alternative embodiment in which CMRTS unit (1300) isconfigured to feed multiple electrical RF or data outputs (1302 to1308), and is further configured to connect directly to a singlehousehold (1400), which may be a single house or a multiple unitfacility such as an office building or apartment house.

An additional advantage of placing the improved optical fiber nodesproximate to or attached to a house or other building (which may be amulti-household/office building) is that use of other protocols,including TDD protocols, taught previously (e.g. application 61/511,395,incorporated herein by reference) may also be used as desired.

1. A remote CMTS fiber node (CMRTS) system for a Hybrid Fiber Cable (HFC) network, comprising: at least one software controllable RF modulator device capable of encoding selected portions of digitally encoded second optical fiber signals into a second set of RF waveforms; at least one software controllable switch that can be remotely directed to select at least some of said second optical fiber signals (selected second optical signals) and direct said at least one software controllable RF modulator device to encode said selected second optical signals into said second set of RF waveforms at a selected set of frequencies (remotely generated RF signals); at least one remotely software controllable RF packet processor capable of detecting upstream data carried by CATV RF upstream signals generated by at least one cable modem, digitally repackaging said upstream data, and retransmitting said upstream data as a third upstream digital optical fiber signal; wherein said at least one software controllable RF modulator device, and/or said software controllable RF packet processor comprise at least one FPGA and DSP devices that are capable of being remotely configured by software to implement MAC and PHY with additional non-DOCSIS functionality, a full set of DOCSIS functionality, or a subset of the standard DOCSIS upstream and downstream functions; in which the functioning of said at least one software controllable switch, the functioning of said RF modulator device and the functioning of said at least one remotely software controllable RF packet processor are controlled by a remote virtual shelf manager system.
 2. The system of claim 1, wherein said software controllable RF modulator device's at least one FPGA device is configured using FPGA configuration data that is either stored in memory at said remote CMTS fiber node, or downloaded from said remote virtual shelf manager system; and said software controllable RF modulator device's at least one DSP device is programmed using DSP software that is either stored in memory at said remote CMTS fiber node, or downloaded from said remote virtual shelf manager system.
 3. The system of claim 2, wherein said software controllable RF modulator device's at least one FPGA device and at least one DSP device are configured to implement a filter bank type RF modulator and transmitter.
 4. The system of claim 2, wherein said software controllable RF modulator device's at least one FPGA and DSP devices are configured to produce QAM or CDMA or OFDM waveforms, and said second set of RF waveforms are QAM or CDMA or OFDM waveforms.
 5. The system of claim 2, wherein said software configurable RF modulator device is further configured to implement an RF modulator and transmitter that pre-distorts or customizes said second set of RF waveforms to correct for RF signal impairments in at least part of the Cable portion of said Hybrid Fiber Cable (HFC) network.
 6. The system of claim 1, wherein said software controllable RF packet processor's at least one FPGA and DSP devices are configured into MAC and PHY units that function as at least one TDMA burst receiver or CDMA receiver or OFDM receiver.
 7. The system of claim 6, wherein said software controllable RF packet processor's at least one FPGA device is configured using FPGA configuration data that is either stored in memory at said remote CMTS fiber node, or downloaded from said remote virtual shelf manager system; and said software controllable RF packet processor at least one DSP device is programmed using DSP software that is either stored in memory at said remote CMTS fiber node, or downloaded from said remote virtual shelf manager system.
 8. The system of claim 6, wherein said software controllable RF packet processor's at least one FPGA and DSP devices are configured to implement at least one filter bank receiver and/or at least one superheterodyne receiver.
 9. The system of claim 6, wherein said software controllable RF packet processor is further configured to implement at least one receiver with the capability to equalize or adjust said CATV upstream RF signals to correct for RF signal impairments in at least part of the cable portion of said Hybrid Fiber Cable (HFC) network.
 10. The system of claim 1, in which the virtual shelf manager system comprises a device configuration database with at least CMRTS identifier fields, cable modem identification data fields, the privileges of users associated with said cable modem identification fields (user privilege fields), available DOCSIS channels, available IP addresses, instructions to configure said at least one software controllable switch, and instructions to configure said remotely software controllable RF packet processor; at least one processor; and hardware and software capable of sending and receiving data packets to and from a plurality of remote CMRTS units.
 11. The system of claim 10, in which said virtual shelf manager system sends data packets to said remotely software controllable RF packet processor(s) to detect upstream cable modem identification data transmitted by at least one newly initialized cable modem and transmit said modem identification data to said remote virtual shelf manager system.
 12. The system of claim 10, in which said device configuration database additionally comprises a plurality of FPGA configuration data and DSP program data, and wherein at least some of said FPGA configuration data and DSP program data are downloaded from said remote virtual shelf manager system to said remote CMTS fiber node.
 13. The system of claim 1, further comprising a first optical to RF (radio frequency) conversion device that directly converts a first set of RF modulated optical fiber signals to a first set of CATV RF signals.
 14. A method for enhancing the data carrying capacity of a hybrid fiber cable (HFC) network with a cable head, an optical fiber network, a plurality of optical fiber nodes, a plurality of individual CATV cables connected to said plurality of optical fiber nodes, and a plurality of individual cable modems, each with differing data requirements, connected each of said individual CATV cables, comprising: obtaining at least one remote CMTS fiber node (CMRTS), said remote CMTS fiber node comprising: at least one software controllable RF modulator device capable of encoding selected portions of digitally encoded second optical fiber signals into a second set of RF QAM waveforms; at least one software controllable switch that can be remotely directed to select at least some of said second optical fiber signals (selected second optical signals) and direct said at least one software controllable RF modulator device to encode said selected second optical signals into said second set of RF waveforms at a selected set of frequencies (remotely generated RF signals); at least one remotely software controllable RF packet processor capable of detecting upstream data carried by CATV RF upstream signals generated by at least one cable modem, digitally repackaging said upstream data, and retransmitting said upstream data as a third upstream digital optical fiber signal; wherein said at least one software controllable RF modulator device, and/or said software controllable RF packet processor comprise at least one FPGA and DSP devices that are capable of being remotely configured by software to implement MAC and PHY with additional non-DOCSIS functionality, a full set of DOCSIS functionality, or a subset of the standard DOCSIS upstream and downstream functions; and controlling the functioning of said at least one software controllable switch, the functioning of said RF modulator device and the functioning of said at least one remotely software controllable RF packet processor using a remote virtual shelf manager system.
 15. The method of claim 14, further configuring said software controllable RF modulator device's at least one FPGA device using FPGA configuration data that is either stored in memory at said remote CMTS fiber node, or by downloading said FPGA configuration data from said remote virtual shelf manager system; and further programming said software controllable RF modulator device's at least one DSP device using DSP software that is either stored in memory at said remote CMTS fiber node, or by downloading said DSP software from said remote virtual shelf manager system.
 16. The method of claim 15, further configuring said software controllable RF modulator device's at least one FPGA device and at least one DSP device to implement a filter bank type RF modulator and transmitter.
 17. The method of claim 15, further configuring said software controllable RF modulator device's at least one FPGA and DSP devices to produce QAM or CDMA or OFDM waveforms, wherein said second set of RF waveforms are thus QAM or CDMA or OFDM waveforms.
 18. The method of claim 15, further configuring said software configurable RF modulator device to implement an RF modulator and transmitter that pre-distorts or customizes said second set of RF waveforms to correct for RF signal impairments in at least part of the Cable portion of said Hybrid Fiber Cable (HFC) network.
 19. The method of claim 14, further configuring said software controllable RF packet processor's at least one FPGA and DSP devices into MAC and PHY units that function as at least one TDMA burst receiver, CDMA receiver, or OFDM receiver.
 20. The method of claim 19, further configuring said software controllable RF packet processor's at least one FPGA device using FPGA configuration data that is either stored in memory at said remote CMTS fiber node, or by downloading said FPGA configuration data from said remote virtual shelf manager system; and programming said software controllable RF packet processor's at least one DSP device using DSP software that is either stored in memory at said remote CMTS fiber node, or by downloading said DSP software from said remote virtual shelf manager system.
 21. The method of claim 19, further configuring said software controllable RF packet processor's at least one FPGA and DSP devices to implement at least one filter bank receiver and/or at least one superheterodyne receiver.
 22. The method of claim 19, further configuring said software controllable RF packet processor to implement at least one receiver with the capability to equalize or adjust said CATV upstream RF signals to correct for RF signal impairments in at least part of the cable portion of said Hybrid Fiber Cable (HFC) network.
 23. The method of claim 14, in which the virtual shelf manager system comprises a device configuration database with at least CMRTS identifier fields, cable modem identification data fields, the privileges of users associated with said cable modem identification fields (user privilege fields), available DOCSIS channels, available IP addresses, instructions to configure said at least one software controllable switch, and instructions to configure said remotely software controllable RF packet processor; at least one processor; and hardware and software capable of sending and receiving data packets to and from a plurality of remote CMRTS units.
 24. The method of claim 23, further using said virtual shelf manager system to send data packets to said remotely software controllable RF packet processor(s) to detect upstream cable modem identification data transmitted by at least one newly initialized cable modem and transmitting said modem identification data to said remote virtual shelf manager system.
 25. The method of claim 23, in which said device configuration database additionally comprises a plurality of FPGA configuration data and DSP program data, further downloading at least some of said FPGA configuration data and DSP program data from said remote virtual shelf manager system to said remote CMTS fiber node.
 26. The method of claim 14, further using a first optical to RF (radio frequency) conversion device to directly converts a first set of RF modulated optical fiber signals to a first set of CATV RF signals. 